The GHK12X2H has all of the features of the original    GHK12X2 plus set point heat and an additional temperature sensor. It has a programmable temperature settings in DIF, DAY    & NITE stages; 2 HEAT, 4 COOL steps with automatic and    manual settings; TIMER and ALARM outputs; 1 or 2 zones;    VENT stage for dehumidification; STATISTICS (min, max, and    7 days of temperature averages) - along with set point heat for    hot water heat or heated beds. The GHK12X2C is compatible    with CIS software to connect multiple controllers to a personal computer for programming and monitoring.