Designed to work with the HRM USA Chest Transmitters, select Polar Chest Transmitters. The HeartRateMonitors USA soft chest strap is designed with most heart rate trainers in mind! Comfortable and machine washable. This strap allows Polar users to get the chest strap that best fits their chest size, and provides a secondary option for their transmitter chest straps. Works with Polar H1, H2, H6, H7 H10, H9, Wearlink &, Bluetooth Transmitters . Also works with the Garmin Dual Transmitter. Strap Sizes XSmall-Small 22 to 33 inches Medium-XXLarge 28 to 52 inches XXXLarge 42 to 77 inches Specs Made with Polyamide, Polyurethan, and Elastan. Latex Free Stainless steel snaps, nickel free. Tested & safe coloring agents. *Not Machine Washable*