The Pool Mate uses state of the art accelerometers to measure the movement of the wrist during the swim stroke. Advanced digital signal processing techniques & software algorithms have been developed by our engineers to pick out the stroke & lap information for the recognised swimming strokes. Works with Front Crawl, Back stroke, Breaststroke & Butterfly, all sizes of pool over 15 metres or yards & without calibration. FREE SHAMPOO WITH YOUR POOLMATE WATCH!