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. 41mm: Strap fits 130–200mm wrists. 45mm: Strap fits 140–210mm wrists. Works with all versions of Apple Watch. Material: Fluoroelastomer