Compatible with Polar: CS100s, CS200s, CS300s, CS400s, FS2s, FS3s, FT1, FT2, FT4, FT7, FT40s, FT60s, FT80s, RS300s, RS400s, Sizing Choices: Measure just under the breasts/chest area Medium (25-54 Inches) Large (33-63 Inches) Small (23-47 Inches) Coding prevents cross-talk from other electrical devices. Slim, light and waterproof. Transmits your heart rate to your wrist unit ECG (electrocardiogram) accurately. It is suggested that the battery (ce0537) be replaced by Polar. Great for swimmers - Fully water resistant making them the most effective exercise tools for measuring your heart rate while involved in water sports. Delivers 2,500 hours of operation, or 5 years of use exercising at 10 hours a week.
Polar T31C Coded Transmitter with Medium Elastic Strap PT-31C