Time initiated temperature, pressure or time terminated models available;High-amp switch contacts: 40 Amps, 2 HP;Positive slider bar switch design assures positive electrical contact and wipes the contact surface of contaminates;Temperature or pressure terminated models are designed for defrost termination using an external temperature or pressure device;Safety back-up mechanical time-driven defrost termination;Heavy-duty synchronous design drive motor;Choice of three contact arrangements;Adjustable frequency of defrost initiation from 1 to 6 cycles per day with a minimum of 4 hours between successive operations;Adjustable back-up defrost termination from 4 to 110 minutes in 2 minute increments;Heavy-duty steel enclosure with knockouts (on the bottom, back and sides) and hasp and staple padlock;All 8240 models have an adjustable cut-in pressure dial calibrated from 36-110 pounds for R12, R22, R502