The Polar Equine T52H Coded transmitter can be used with most (see below) Polar receivers to measure a horse"s heart rate. The coded transmission reduces the risk of cross-talking in a crowded area. You will not read the heart rate of the horse next you. The T52H coded transmitter is mandatory with receivers measuring speed. The heart generates an electrical signal that can be measured on the skin. The Polar Equine transmitter contains two electrodes to detect the electrical signal during every heart beat and sends this information continuously and wirelessly to the wrist receiver. The electrodes are mounted on a sealed transmitter that is attached to the saddle. Polar"s unique patented one-piece molded construction makes the Polar Equine transmitter the only 100% waterproof equine heart rate transmitter available. Compatibility: It is not compatible with RS800, CS600 or any products using the Polar W.I.N.D. technology. If you need a W.I.N.D. horse transmitter, please look at the Polar Equine Wearlink W.I.N.D. transmitter