The sports band made from a special high-performance fluoroelastomer is durable, robust, and surprisingly soft. The soft, dense material feels good on the skin and conforms to the wrist. The innovative pin closure ensures a secure fit. You can pair most bands with any Apple Watch Series 3 case or newer cases of the same size. 41 mm bands fit 38 mm and 40 mm cases. 45 mm bands fit 42 mm, 44 mm, and 49 mm cases.