Made from a custom high-performance fluoroelastomer, the Sport Band is durable and strong, yet surprisingly soft. The smooth, dense material drapes elegantly across your wrist and feels comfortable next to your skin. An innovative pin-and-tuck closure ensures a clean fit. You can match these straps with any Apple Watch Series 4 case of the same size. They also work with all previous versions of Apple Watch, including Apple Watch Series 3. Physical specificationW40, . FeaturesAccessories included: Apple Watch Sport Band.