The Polar Pro Soft Chest Strap works with all Polar heart rate monitors and comes in a choice of sizes to suit all users. Made with a soft material, a secure buckle and silicone dots to help prevent slipping, the chest strap is extremely comfortable to wear and will stay in place even during the most intense workouts. The electrodes on the soft strap are designed to prevent interference from other sources so that it can more accurately pick up your heart’s electrical signal. This helps to ensure your heart rate monitoring is as precise as it can be. This chest strap is available in three sizes: XS-S, M-XXL and XXXL.