Zinc alloy material; heating element encased by head w/stud type electric al connection 12 vdc operating voltage; head has the rmostatic type valve w/0.250 in. Pipe connection on one side; three thd mtg holes 0.250-20 unc thd size; head fits on 5.500 in. Id tank or chamber; 4.250 in. H, 5.969 in. Dia