Honeywell Round Manual Non-Programmable Thermostat, Relay Switch, Terminal Designations: R, W, Y, Thermistor Sensor, 1 Stage, 20 to 30 VAC, 5 to 90% Humidity, Round Mount, Premier White, 3-11/16 inch diameter x 1-3/4 inch D
The Round thermostats provide electronic control of 24VAC heating and cooling systems with the classic twist to set diameterl.