The Braeburn 4030 is universal auto changeover thermostat is a 4.25” high x 5.12” wide x 1” deep, powered with either 24 Volt AC or with two “AA” Alkaline batteries (3.0 Volt DC). In the event of a power failure, the unit will retain all user, installer and program settings. The thermostat is compatible with low voltage single stage gas, oil, or electric heating or cooling systems, and single stage heat pumps with auxiliary heat. Also compatible with 250mv – 750mv millivolt heating only systems and 2 or 3 wire hydronic zone systems. The thermostat has an adjustable bright blue backlight display, separate sub-base and multi-level keypad lockout. Temperature control range is between 45 and 90 F (7 and 32 C), accuracy of /- 1 F ( /- .5 C) and operating humidity range between 5% and 95% relative humidity. The thermostat includes separate installer and user setup modes, permanent non-volatile memory to retain user settings, filter, UV and humidifier pad check monitor, adaptive recovery mode (ARM™), programmable fan mode, residual cooling fan delay, indoor or outdoor remote sensor capability and multi-function dry contact input.