Ph D Fitness Overview The H2 sensor is compatible with the FT1, FT2, FT4, FT7, FT40, FT60, FT80, RS100, RS300X, RS400, RCX5, CS100, CS200 & the CS300 monitors. Very comfortable to wear & very reliable, can even be used whilst swimming. Look out for the Polar symbol on any piece of equipment at the gym as this product is likely to be compatible with it.