A great watch for Triathletes, the Polar RS800CX multi-sport heart rate monitor watch offers a complete system for planning, monitoring, and analyzing every part of your training. This particular version of the RS800CX is equipped with a host of valuable tools, including a built-in altimeter, a WearLink W.I.N.D. heart rate transmitter with a soft textile chest strap, a copy of Polar ProTrainer 5 software, and a S3 stride sensor that helps you measure your running speed, distance, cadence and average stride length.