Front of Thermostat dimensions: 4-1/2" Wide x 6-1/8" Tall x 1/8" Thick beyond surface. Cut in wall dimensions: 3-1/4" wide x 5-3/8" tall x 1-7/8" deep Large touch-screen interface. Runs on 2 AA batteries and/or HVAC power. Full or partial system lock functionality. Easy-to-read white backlit display. May reduce your heating/cooling bills by up to 33% when used as instructed. Not for use with 115/230 VAC wall or baseboard electric heaters. Step 1. Cut hole in wall. 2. Insert wall box and wire thermostat Tools needed for installation: Phillips screwdriver, 2 AA Batteries required to operate, Hand saw and/or utility knife.