DESC: Polar Heart Rate Straps work with most cardio exercise machines at gyms and health clubs worldwide to allow you to monitor your heart rate 'hands-free' while working out. Check with your health club to ensure their equipment is Polar compatible.Taking comfort and function to another level, the new Polar WearLink™ is the first soft transmitter belt ever produced. With the exclusive Polar transmitter technology engineered right into the fabric strap, the WearLink™ will fit any body shape and allow full freedom of movement. It will change the way you exercise. WearLink™ Transmitter Features:Electrode engineered into fabric strapCoded technology which eliminates interference from other HRM usersChangeable batteryBattery life (2 years)Replaceable fabric strap (Life of strap - 100 machine washings)Water resistantWearLink™ is compatible with all S Series Monitors and comes standard with the S625X and S810 models and all M Series models.