Sennheiser hd 180 đánh giá

Tai nghe Sennheiser HD180 Bass: HD201 là chiếc tai nghe giá rẻ có độ chi tiết và trong trẻo rất cao tuy nhiên âm bass lại tỏ ra hơi khiêm tốn thì rất may mắn là điều đó đã không xảy ra trên HD180 mặc dù Hd180 không phải là dạng tai nghe có âm bass quá nhiều tuy nhiên nó vẫn cung cấp một lượng bass rất vừa vặn cho những bản nhạc không còn cảm giác thiếu thốn nữa Không giống như âm bass bạo lực của các dòng tai nghe giá rẻ khác thì HD180 mang âm bass vừa vặn và tập trung chủ yếu vào mid bass, âm bass chưa được sâu và hơi thiếu lực, cũng dễ hiểu vì tầm giá này khó có thể đòi hỏi một âm bass sâu và có lực được, bù lại thì âm bass HD180 tỏ ra khá dễ chịu khi nghe với âm sub bass nhẹ nhàng kết hợp với mid bass có độ nảy tốt và tốc độ khá nhanh và căng tạo cảm giác hưng phấn hơn khi nghe nhạc. Mid: Nếu quen với kiểu âm mid chìm nịnh tai thì âm mid của HD180 sẽ khác hoàn toàn, bạn có thể thích thú hoặc sẽ cảm thấy lạ lẫm với âm mid này, âm mid không mượt mà và khá khô, HD180 có mid tiến hơn so với 2 dải còn lại, giọng ca sĩ được thể hiện rất rõ ràng, rất hay nếu các bạn thích nghe những bản nhạc voical hoặc những ca sĩ có kỹ thuật điêu luyện. Treble: Với một chiếc tai nghe giá rẻ ta rất khó đòi hỏi một âm treble hay và hoàn thiện được, âm treble của HD180 chưa được trau chuốt kỹ, vẫn còn khá mỏng và hơi gắt và mất kiểm soát khi lên quá cao tuy nhiên với những ai không quá khó tính về âm thanh thì điều này hoàn toàn có thể chấp nhận được. Âm trường, chi tiết: Có lẽ đây là điểm mạnh nhất và cũng là điểm mạnh nhất của HD180, sở hữu mức giá rất rẻ so với một thương hiệu lớn tuy nhiên độ chi tiết và âm trường của HD180 không hề thua kém những tai nghe đắt tiền. Âm trường HD180 thuộc dạng tốt trong phân khúc tai nghe close, không rộng thênh thang nhưng cũng đáp ứng khá đủ nhu cầu nghe nhạc bình thường Độ chi tiết cực kỳ cao làm nên điểm mạnh cho HD180 và cũng là đặc trưng của tai nghe Sennheiser kể cả những tai nghe giá rẻ của hãng vì sở hữu độ chi tiết đáng nể, các tiếng gảy đàn, gõ phách…đều rất tách bạch và rõ ràng. Tổng kết HD180 là chiếc tai nghe fullsize giá rẻ cực kỳ đáng mua ở mức giá trên dưới 500 nghìn với thương hiệu lớn và nổi tiếng cùng âm bass được cải thiện đáng kể so với HD201 và độ chi tiết cực cao sẽ là giải pháp giải trí tốt phù hợp với túi tiền của nhiều người sử dụng 👉Nơi bán: Hà Nội, Hải Phòng, Toàn Quốc Hình thức thanh toán: tại nhà (COD); Chuyển khoản; Visa Giao hàng nội thành trong vòng 1h; Miễn phí giao hàng! Giao hàng ngoại thành và liên tỉnh: 24h - 48h; Chi phí Theo bảng giá VN POST, VIETTEL POST, TÍN THÀNH ☎️ TƯ VẤN TRỰC TIẾP <<<0948325555 để nhận được nhiều ưu đãi #VietAudio.

*Happy Shopping!!! Replacement Ear Pads Cushion for Sennheiser HD201 HD180 HD201S Headphones Description: The item is a pair of Ear Pads For Sennheiser HD201 HD180 HD201S Headphones. This pair of ear cushions is made of soft PU Leather, which makes your wearing very cozy and comfortable. With it, you can enjoy your stereo music to the fullest. Features: -Ideal replacement for you lost or broken ear cushions -It is snap easily into your headphone -Made of Quality soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening Specification: Quantity: 1 pair Material: PU Leather Color: Black Suitable For Sennheiser HD201 HD180 HD201S Headphones. The ear pads size: Approx. 100*77*18mm Note: Not Original item, High quality items guarantee!! The Headphone not included. Included: 1 X A Pair of Ear Cu

Đệm thay thế cho tai nghe Sennheiser HD180, HD201, HD201S - Hàng chính hãng Với các mẫu tai nghe chụp tai sau một thời gian sử dụng thì mút bọc (đệm) tai nghe bắt đầu bị bong tróc và rách, làm mất đi vẻ đẹp ban đầu, giảm chất lượng âm thanh của tai nghe và gây khó chịu cho người sử dụng. Nếu bạn đang cần thay thế đệm tai nghe, hãy đến ngay các chi nhánh của XVA trên toàn quốc. Xuân Vũ Audio hiện đang cung cấp các loại đệm tai nghe của các hãng như ATH, Bose, Sennheier, Sony, AKG, Beats,… có chất lượng tốt với mức giá rất phải chăng. Các loại đệm tai nghe do XVA cung cấp đảm bảo chất lượng tốt, đa dạng mẫu mã, bền, đẹp, dễ dàng thay thế và sử dụng. Các tai nghe hỗ trợ - Phù hợp với tai nghe Sennheiser HD180, HD201, HD201S - Không phù hợp với các mẫu tai nghe khác Đệm tai thay thế có thể sử dụng lâu dài, bề mặt mịn và cảm giác thoải mái khi đeo. #xva #hangchinhhang #demtainghe #ea

Welcome to our store-shoppingeverydays------------------------------- We Offer Various Electronic items. Include:Computer Accessories、phone Accessories Our products are from China 1 Pair Headphones Ear Pads PU Leather Headset Replacement Cushions for Sennheiser HD201 HD180 HD201S Feature: - It is snap easily into your headphone. - Ideal replacement for you lost or broken ear cushions. - Made of soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening. Specification: Material: PU Leather Ear Pads Size: Approx. 100 X 77 X 18mm/3.94 X 3.03 X 0.71" Suitable: For Sennheiser HD201 HD180 HD201S Note: -Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! -Please allow 1-3mm measuring deviation due to manual measurement. Included: 1 Pair X Ear Cus

Features: 1. Compatible with for Sennheiser HD201 HD180 HD201S headphones. 2. Enhance the bass performance of the headphones to make you enjoy the music. 3. Made of high-quality soft and comfortable sponge, durable. 4. Soft and high elasticity, easy to listen to music. Replace your lost or damaged ear pads. 5. Easy to install without any complicated procedures. Specification: Material: Cotton Color: Black Size: Approx. 10 * 7.8 * 1.9cm / 3.94 * 3.07 * 0.75inch Weight: Approx. 17 g Package List: 1 * A Pair of Ear Pads (left and rig

___________________❀Alwaysonline❀___________________ Welcome to our store, we insist on to sell the best quality items. ✔Ready Stock ✔ ✔Quality Checked ★Surprises for you★ ☞Shop Voucher: Get More Discount ☞Follow Shop: Free Gifts ★★Attention Please★★ ✌We will be based on your guests in your country to send the corresponding adapter plug. _______________❀Product Information❀______________ Features: -Compatible with for Sennheiser HD201 HD180 HD201S headphones. -Enhance the bass performance of the headphones to make you enjoy the music. -Made of high-quality soft and comfortable sponge, durable. -Soft and high elasticity, easy to listen to music. Replace your lost or damaged ear pads. -Easy to install without any complicated procedures. Specification: Material: Cotton Color: Black Size: Approx. 10 * 7.8 * 1.9cm / 3.94 * 3.07 * 0.75inch Weight: Approx. 17 g Package List: 1 * A Pair of Ear Pads (left and r

Replacement Ear Pads Cushion for Sennheiser HD201 HD180 HD201S Headphones Description: The item is a pair of Ear Pads For Sennheiser HD201 HD180 HD201S Headphones. This pair of ear cushions is made of soft PU Leather, which makes your wearing very cozy and comfortable. With it, you can enjoy your stereo music to the fullest. Features: 1. Ideal replacement for you lost or broken ear cushions 2. It is snap easily into your headphone 3. Made of Quality soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening Specification: Quantity: 1 pair Material: PU Leather Color: Black Suitable For Sennheiser HD201 HD180 HD201S Headphones. The ear pads size: Approx. 100*77*18mm Note: Not Original item, High quality items guarantee!! The Headphone not included. Included: 1 X A Pair of Ear Cu

We are a professional earphone accessories merchant, we promise that if our accessories are not suitable, we will refund the full amount, please rest assured to buy! If you have any questions, please contact customer service.Brand Name: Vocalism Principle:Balanced Armature Communication:Wired Style:Headphone Wireless Type:Blue

1pc Headphones Ear Pads PU Leather Headset Replacement Cushions for Sennheiser HD201 HD180 HD201S Feature: - It is snap easily into your headphone. - Ideal replacement for you lost or broken ear cushions. - Made of soft comfortable PU leather, durable flexible, for hours of comfortable listening. Specification: Material: PU Leather Ear Pads Size: Approx. 85 X 70 X 18mm/3.34 X 2.76 X 0.71" Suitable: For Sennheiser HD201 HD180 HD201S Note: 1. Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! 2. Please allow 1-3mm measuring deviation due to manual measurement. Included: 1pc X Ear Cus

Dear, welcome to myhomever, here is the latest season's products, you are welcome to choose the purchase, we will give you the best service experience, I wish you a happy day ~ for product details, please go down to see ~ Replacement Ear Pads Cushion for Sennheiser HD201 HD180 HD201S Headphones Description: The item is a pair of Ear Pads For Sennheiser HD201 HD180 HD201S Headphones. This pair of ear cushions is made of soft PU Leather, which makes your wearing very cozy and comfortable. With it, you can enjoy your stereo music to the fullest. Features: 1. Ideal replacement for you lost or broken ear cushions 2. It is snap easily into your headphone 3. Made of Quality soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening Specification: Quantity: 1 pair Material: PU Leather Color: Black Suitable For Sennheiser HD201 HD180 HD201S Headphones. The ear pads size: Approx. 100*77*18mm Note: Not Original item, High quality items guarantee!! The Headphone not included. Included: 1 X A Pair of Ear Cu

1 Pair Replacement PU Leather Foam Ear Pads Cushions for Sennheiser HD201 HD180 HD201S Headphones Features: - Ear pads for Sennheiser HD201 HD180 HD201S headphones. - Made of high-quality PU leather, durable and flexible, allow wearing for hours. - Soft foam blocks outside noise. - Replace the previous ear pads and turn the headphones into new ones. - Easy to install, just remove the previous one and install the new one. Specifications: Material: PU Leather Size: 95*70*15mm/3.74*2.76*0.59" Notes: 1. There may be slight size deviations due to manual measurement, different measuring methods and tools. 2. The picture may not reflect the actual color of the item because of different photographing light, angle and display monitor. Included: 1 Pair X Replacement Ear

Compatible with (but not limited to): Sennheiser HD201 HD206 HD180 HD201S Headphones. ---------------------------------------------------------------------------------- Who would have thought that by just replacing the earpads of your headphones, you get to listen to your favorite music or watch your most awaited movie with great precision and clear sounds. The misodiko Premium Noise Cancelling Memory Foam Earpads has got what you need and more! Stop using your old and worn-out ear pads and replace them with these brand new and high quality pads that's just right for you. They are designed to not only give you comfort but also has the ability to block out noise and coming from your surroundings. They are Easy to Install, so please don't settle on using your old and worn out ear pads. Replace them, Or better yet, upgrade your headphones when you get the misodiko Premium Ear Cushions. You can be sure that what you get is a high quality and durable earpads that can last you a long time. There is no time to wait. Grab one of these premium earpads t

1 Pair Headphones Ear Pads PU Leather Headset Replacement Cushions for Sennheiser HD201 HD180 HD201S Feature: - It is snap easily into your headphone. - Ideal replacement for you lost or broken ear cushions. - Made of soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening. Specification: Material: PU Leather Ear Pads Size: Approx. 100 X 77 X 18mm/3.94 X 3.03 X 0.71" Suitable: For Sennheiser HD201 HD180 HD201S Note: -Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! -Please allow 1-3mm measuring deviation due to manual measurement. Included: 1 Pair X Ear Cus

1 Pair Headphones Ear Pads PU Leather Headset Replacement Cushions for Sennheiser HD201 HD180 HD201S Feature: - It is snap easily into your headphone. - Ideal replacement for you lost or broken ear cushions. - Made of soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening. Specification: Material: PU Leather Ear Pads Size: Approx. 85 X 70 X 18mm/3.34 X 2.76 X 0.71" Suitable: For Sennheiser HD201 HD180 HD201S Note: -Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! -Please allow 1-3mm measuring deviation due to manual measurement. Included: 1 Pair X Ear Cus

Hd201 hd180 hd201s Description: 100%, high quality Characteristics: Good substitute for old/damaged/damaged/bad headphone/headphone/headband cover. Soft and soft ear pads fit everyone 's ears, effectively isolating the noise from outside. Ear pads enhance the fidelity of audio, it also provides a more vivid voice. Easy to install and dismantle, no tools required, easy to use. Sennheiser hd201 hd180 hd201s. Ear mattress, excluding other parts demonstration in the picture Product specifications: Number: 1 pair Material: Protein leather + Sponge Color: Black Applicable to: Sennheiser hd201 hd180 hd201s. Ear pad size: 95x75 x 15mm/3.74x2.95x0.59 in Notes: - due to manual measurements, error of 0-1 centimeters is allowed. Please make sure you don 't mind your bid. - differences between different monitors, the picture may not reflect the actual color of the project. Thank you Packing includ

Dear, welcome to vernesss, here is the latest season of electronic products, I hope you like it~ 1 Pair Headphones Ear Pads PU Leather Headset Replacement Cushions for Sennheiser HD201 HD180 HD201S Feature: - It is snap easily into your headphone. - Ideal replacement for you lost or broken ear cushions. - Made of soft comfortable PU leather, durable & flexible, for hours of comfortable listening. Specification: Material: PU Leather Ear Pads Size: Approx. 85 X 70 X 18mm/3.34 X 2.76 X 0.71" Suitable: For Sennheiser HD201 HD180 HD201S Note: 1. Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! 2. Please allow 1-3mm measuring deviation due to manual measure

Giới thiệu về sản phẩm - Tai nghe khá nhẹ , thiết kế khi đeo cảm thấy rất thoải mái - Dây tín hiệu dài tận 3m. Sử dụng Jack cắm 3,5" và có thêm Jack chuyển đổi sang 6,3". Nghe khá được với giá thành rất rẻ - Màng loa driver Dynamic, trở kháng 24Ohm,SPL 108dB, dải tần 21-18000 Hz - Tai nghe phù hợp với các dòng nhạc trữ tình,nhạc vàng, rock, pop.. với âm trầm vừa đủ cân bằng với các dải âm thanh khác ở tầm tiền này, âm thanh rất trong trẻo. THÔNG SỐ KĨ THUẬT SẢN PHẨM DISABLE ADD TO CART Không HÃNG SẢN XUẤT Sennheiser BẢO HÀNH 02 năm MÀU SẮC Black COUNTRY OF MANUFACTURE Đức MỤC ĐÍCH SỬ DỤNG Android, Blackberry, Gaming, iPhone IMPEDANCE 24 Ω FREQUENCY RESPONSE 21 - 18,000 Hz SOUND PRESSURE LEVEL (SPL) 108dB CONNECTOR 3.5mm, 6.3mm CABLE LENGTH 3m TRANSDUCER PRINCIPLE Dynamic WHAT'S IN THE BOX? HD180 Headphones ¼” (6.3 mm) stereo jack ad

Lucky every day.1 Pair Headphones Ear Pads PU Leather Headset Replacement Cushions for Sennheiser HD201 HD180 HD201S Feature: - It is snap easily into your headphone. - Ideal replacement for you lost or broken ear cushions. - Made of soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening. Specification: Material: PU Leather Ear Pads Size: Approx. 85 X 70 X 18mm/3.34 X 2.76 X 0.71" Suitable: For Sennheiser HD201 HD180 HD201S Note: -Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! -Please allow 1-3mm measuring deviation due to manual measurement. Included: 1 Pair X Ear Cus

Compatible with Sennheiser HD180, HD201, HD449 Headphones Protein Leather for Extra Comfort, Memory Foam to Enhance Noise Blocking Product Dimensions: 3.9 X 3.1 X 0.6 inches (9.5 X 7.5 X 1.5 cm) Package Contents: Headphone Ear Pad X 2, Geekria Warranty Geekria SureFit Guarantee: 100% Money Back if Not Fit Compatible Headphone: - Sennheiser HD180, HD201, HD449 Note: - Replacement ear cushion only, Headphone is not included. Package Includes: - 2 x Replacement ear cushion - 1 x Geekria Warranty (Colors shown in pictures may slightly differ from actual product due to lighting and color settings.) This product is sold exclusively by GeekriaDirect. Only buy from GeekriaDirect store to get genuine Geekria(TM) products with superb customer service. *The product is NOT made by the Sennheiser Inc. It does not bear any trademarks that are owned by the Sennheiser Inc. and the seller is NOT affiliated with the Sennheiser Inc. in an

We are a professional earphone accessories merchant, we promise that if our accessories are not suitable, we will refund the full amount, please rest assured to buy! If you have any questions, please contact customer service.Brand Name: Item Type:Ear Pads Packa

Factory direct sales, first-hand source Tips for attention to sales Be careful in tendering, after tendering, application for cancelation of order, need customs to show shipment Overtaken size: 45cm 30cm 30cm, weight 5 kg Delivery on time (Within 6 days) Not taking the goods will affect your credib

♡ Replacement Ear Pads Cushion for Sennheiser HD201 HD180 HD201S Headphones Description: The item is a pair of Ear Pads For Sennheiser HD201 HD180 HD201S Headphones. This pair of ear cushions is made of soft PU Leather, which makes your wearing very cozy and comfortable. With it, you can enjoy your stereo music to the fullest. Features: -Ideal replacement for you lost or broken ear cushions -It is snap easily into your headphone -Made of Quality soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening Specification: Quantity: 1 pair Material: PU Leather Color: Black Suitable For Sennheiser HD201 HD180 HD201S Headphones. The ear pads size: Approx. 100*77*18mm Note: Not Original item, High quality items guarantee!! The Headphone not included. Included: 1 X A Pair of Ear Cu

Happy every day.1 Pair Headphones Ear Pads PU Leather Headset Replacement Cushions for Sennheiser HD201 HD180 HD201S Feature: - It is snap easily into your headphone. - Ideal replacement for you lost or broken ear cushions. - Made of soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening. Specification: Material: PU Leather Ear Pads Size: Approx. 85 X 70 X 18mm/3.34 X 2.76 X 0.71" Suitable: For Sennheiser HD201 HD180 HD201S Note: -Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you! -Please allow 1-3mm measuring deviation due to manual measurement. Included: 1 Pair X Ear Cus

Features: 1. Compatible with for Sennheiser HD201 HD180 HD201S headphones. 2. Enhance the bass performance of the headphones to make you enjoy the music. 3. Made of high-quality soft and comfortable sponge, durable. 4. Soft and high elasticity, easy to listen to music. Replace your lost or damaged ear pads. 5. Easy to install without any complicated procedures. Specification: Material: Cotton Color: Black Size: Approx. 10 * 7.8 * 1.9cm / 3.94 * 3.07 * 0.75inch Weight: Approx. 17 g Package List: 1 * A Pair of Ear Pads (left and rig

Earpads For Sennheiser HD201 HD201S HD180 HD419 429 HD439 HD418 428 438 448. High Quality and Friendly Use -- These ear cushions use soft memory form for noise blocking enhancement and superior leather for ultra soft surface, can providing you comfortable listening experience and longer use. Good Sense of Hearing -- Blocking noise from outside with soft foam. Simple Quick Replacement -- Cushions align with mounting posts inside the headphone earcups, snap easily into p

___________________❀Alwaysonline❀___________________ Welcome to our store, we insist on the lowest price to sell the best quality items. ✔Ready Stock ✔Wholesale Price ✔Quality Checked ★Surprises for you★ ☞Shop Voucher: Get More Discount ☞Follow Shop: Free Gifts ☞“Like” Items: Priority Shipping ( Sent us follow shop screenshot and remark on your order "Free Gift", if not will miss) ★★Attention Please★★ ✌We will be based on your guests in your country to send the corresponding adapter plug. _______________❀Product Information❀______________ Features: 1. Compatible with for Sennheiser HD201 HD180 HD201S headphones. 2. Enhance the bass performance of the headphones to make you enjoy the music. 3. Made of high-quality soft and comfortable sponge, durable. 4. Soft and high elasticity, easy to listen to music. Replace your lost or damaged ear pads. 5. Easy to install without any complicated procedures. Specification: Material: Cotton Color: Black Size: Approx. 10 * 7.8 * 1.9cm / 3.94 * 3.07 * 0.75inch Weight: Approx. 17 g Package List: 1 * A Pair of Ear Pads (left and rig

1 Pair Replacement PU Leather Foam Ear Pads Cushions for Sennheiser HD201 HD180 HD201S Headphones Features: - Ear pads for Sennheiser HD201 HD180 HD201S headphones. - Made of high-quality PU leather, durable and flexible, allow wearing for hours. - Soft foam blocks outside noise. - Replace the previous ear pads and turn the headphones into new ones. - Easy to install, just remove the previous one and install the new one. Specifications: Material: PU Leather Size: 95*70*15mm/3.74*2.76*0.59" Notes: 1. There may be slight size deviations due to manual measurement, different measuring methods and tools. 2. The picture may not reflect the actual color of the item because of different photographing light, angle and display monitor. Included: 1 Pair X Replacement Ear

Welcome to my shop, I hope you can choose your favorite products here! Replacement Ear Pads Cushion for Sennheiser HD201 HD180 HD201S Headphones Description: The item is a pair of Ear Pads For Sennheiser HD201 HD180 HD201S Headphones. This pair of ear cushions is made of soft PU Leather, which makes your wearing very cozy and comfortable. With it, you can enjoy your stereo music to the fullest. Features: 1. Ideal replacement for you lost or broken ear cushions 2. It is snap easily into your headphone 3. Made of Quality soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening Specification: Quantity: 1 pair Material: PU Leather Color: Black Suitable For Sennheiser HD201 HD180 HD201S Headphones. The ear pads size: Approx. 100*77*18mm Note: Not Original item, High quality items guarantee!! The Headphone not included. Included: 1 X A Pair of Ear Cu

Replacement Ear Pads Cushion for Sennheiser HD201 HD180 HD201S Headphones Description: The item is a pair of Ear Pads For Sennheiser HD201 HD180 HD201S Headphones. This pair of ear cushions is made of soft PU Leather, which makes your wearing very cozy and comfortable. With it, you can enjoy your stereo music to the fullest. Features: -Ideal replacement for you lost or broken ear cushions -It is snap easily into your headphone -Made of Quality soft comfortable PU leather, durable &amp; flexible, for hours of comfortable listening Specification: Quantity: 1 pair Material: PU Leather Color: Black Suitable For Sennheiser HD201 HD180 HD201S Headphones. The ear pads size: Approx. 100*77*18mm Note: Not Original item, High quality items guarantee!! The Headphone not included. Included: 1 X A Pair of Ear Cu