Factoring your heart rate into your decompression calculations makes diving safer and a lot more fun. A lightweight waterproof ECG (electrocardiogram) transmitter is built into an elastic belt that straps around the chest, directly against the skin. This belt wirelessly transmits your heart rate data to your SCUBAPRO personal dive computer. Data is displayed on the screen, plus is factored into your decompression calculations to create a more personalized dive plan and improve the quality of your diving.