McDonnell & Miller 63 HD Head Mechanism Els PW 17895 Durable Construction: Heavy duty hermetic design Durable Construction: Heavy duty hermetic design minimizes mechanical wear and ensures stable operation in harsh commercial environments The Honeywell 47104807 is a contractor grade 18 2 solid thermostat cable engineered for reliable low voltage control circuits in residential and commercial HVACR applications Heavy Duty Construction: Built to withstand the rapid cycling and chemical environments common in industrial boiler water level management The McDonnell & Miller 63 HD Head Mechanism (Part Number 142600) is a heavy duty field replacement designed for Series 63 low water cut offs