Product details:

Non-coded heart rate transmitter belt includes medium strap that fits 25 to 54 inch chest size Transmits HR data to Polar heart rate monitors using 5kHz transmission and compatible gym equipment Slim, lightweight, and completely waterproof Non coded version (doesnt prevent crosstalk). Coded and non coded version both comes with similar user manual. Non user replaceable battery Kindly refer the user manual attached below for troubleshooting steps and instructions.Works with current models except the CS600 and RS800 but does not eliminate interference (cross-talk) from other units
Includes sealed transmitter and elastic strap(M)
Its purpose is to transmit your heart rate to your wrist unit