Emerson M150 Mechanical Heat/Cool Thermostat for Single-Stage Systems The White-Rodgers M150 single-stage, heat/cool thermostat is an easy-to-operate thermostat with reliable performance. This mercury-free mechanical thermostat features rugged snap-action contacts, adjustable heat anticipator and bimetal thermometer. This thermostat is compatible with single-stage heating and cooling (gas, oil, electric), and heat pump systems without auxiliary heat, as well as millivolt and 3-wire zone valve applications. Features Mechanical heat/cool thermostat for use on single stage heating, cooling and heat pump (without aux) systems Works with 3-wire zone valve and millivolt (750mV) applications Easy to install and use Not compatible with multi-stage systems, heat pump with Aux and electric baseboard (120/240V) Mercury-free thermostat Mechanical heat/cool thermostat Compatible with single-stage and heat pump (no aux) gas, oil, electric sytems Works with 3-wire zone valve and millivolt (750mV) applications Dimensions: 3.5 x 4.5 x 1.5 in. Mercury-free thermostat USA SHIPPING estimates delivery times and we work to get your item to you as quickly as possible and within those times, but please know it may take slightly longer than the estimate.