Phenolic resin base plate w/plastic cover and steel face mtg plate; pish-button closes contacts to actuate magnetic coil; 3 screwtype terminals; coil 1 ea, switchgage 1 ea, battery 1 ea; battery terminal has protective overload fuse; 3.000 in. O/a w, 3.000 in. O/a h, 3.250 in. O/a lg