Compatible Models: This replacement band is compatible with the Whoop 4.0 and Apple Watch 10 9 8 7 6 5 4 3 2 1 SE Ultra, 38/40/41/42 mm (Series 10) or 49/46/45/44/42 mm (Series 3/2/1), hybrid band is compatible with Whoop and Apple Watch models, (not compatible with the WHOOP 5.0, One, Peak, MG, and Life). Easy Replacement: Adjust the band length to your desired size, remove the old band, replace it with the new one, and secure it with the original U-shaped bracket. Available in sizes S (fits wrists 6.0-8.5 inches) and L (fits wrists 6.5-10 inches), it's suitable for both men and women. High-Quality Materials: This Whoop armband/ankle band is made of premium nylon, making it breathable, stretchy, adjustable, and comfortable. Perfect for daily sports activities or exercise. (Note: If your watch band accidentally gets wet, please allow it to air dry before wearing to avoid moisture-induced skin irritation.) Easy Care: Washable, durable, wear-resistant, and non-pill and non-fading. After-Sales Service - If you have any questions, please feel free to contact us and we will respond promptly. Hybrid Band for Whoop4.0 & Apple Watch Combo Band - Stretchy Nylon Hybrid Strap Compatible with Whoop 4.0 & Apple watch 38/40/41/42mm (series 3), Breathable and Comfort