FocusPRO non-programmable digital thermostat provides electronic control of 24-volt (AC) conventional and heat pump systems or 750-millivolt (mV) heating systems. Large, clear, backlit display is easy to read in various lighting conditions. Available in large screen or standard display. Precise comfort control (+/- 1ºF) maintains consistent comfort to the highest level of accuracy. Easy-to-change battery door (flip-out) allows for easy replacement without removing or disassembling the thermostat. Up to 3 heat/2 cool heat pump or up to 2 heat/2 cool conventional. Dual-powered (battery and/or hardwire). Replaces: T874R1384.