Provides continuous, accurate heart rate measurement using both 5kHz and 2.4GHz W.I.N.D. transmission * Transfers heart rate information while swimming with products which support 5kHz transmission* [*FT1, FT2, FT4, FT7, FT40, FT60, FT80, RS100, RS300X, RS400, RCX5, CS100, CS200, CS300 and all similar previous models] * Soft fabric material feels like clothing on the skin * Slim and streamlined connector design * New and improved user-replaceable battery mechanism