Polar RCX5 Base Training System
The Polar RCX5 heart rate monitor training system is designed for endurance athletes who want precise coaching to perfect their training. The base model features full heart rate capability and is fully expandable as your training needs increase. The RCX5 is easily expandable using the wide array of W.I.N.D. accessory sensors, ensuring maximum flexibility across multiple sports. The RCX5 includes the H2 Hybrid transmitter which gives heart rate even while swimming. This makes the RCX5 perfect for triathletes and other multi-sport athletes.
Please see this link for its replacement.