The Polar RCX5 Run Training System (Red) for tri-athletes and endurance athletes looking for better performance. It allows you to create your own sport profiles and supports multisport training through swift switching between sports. The ZoneOptimizer personalizes your sport zones during your warm-up. It improves performance with endurance training programs. The multisport watch gives heart rate even in water with a comfortable hybrid transmitter. It is compatible with polar running, cycling and GPS sensors.