1. This watch sport band is made from High-performance Silicone with air holes for breathability, soft, smooth, durable and strong, comfortable to wear. Metal parts is made from upgrade Stainless Steel so it resolved skin allergy problem.</p> 2. Compatible with all kinds of previous and latest versions Watch SE, Series 7, Series 6, Series 5, Series 4, Series 3, Series 2, Series 1, watch 38mm 40mm 41mm 42mm 44mm 45mm models. </p> 3. Various colors are available. Each color in 4 sizes, please choose your correct size: </p> </b> 38mm/40mm/41mm S/M means Small/Med size will fits 5.1"-7.1" (130mm-180mm) wrists </p> 38mm/40mm/41mm M/L means Med/Large size will fits 5.5"-7.5" (140mm-190mm) wrists</p> 45mm/44mm/42mm S/M means Small/Med size will fits 5.9"-7.9" (150mm-200mm) wrists </p> 45mm/44mm/42mm M/L means Med/Large will fits 6.3"-8.3" 160mm-210mm) wrists</p> 4. 100% Satisfaction Customer Service. If you have any question for our watch sport bands, please be free to Email us by Amazon to get free replacement or refund, thank you!