The garmin hrm tri and hrm swim heart rate transmitter bundle for 920xt and fenix 3 its never been possible to record heart rate accurately during swimming until now with the hrm swim and hrm tri heart rate straps once on the belt is comfortable due to its seamless material and rounded edges the strap remains comfortable during extended hours of training and is designed to be worn under a tri suit the module stores up to 20 hours of heart rate data during swims then forwards it to a com