4” pre-galvanized steel square box, 1-1/2” deep, 21 cubic inches. Welded construction, 1/2” & 3/4” eccentric knockouts and “B” bracket. For use with conduit. Total knockouts: sides 8 – 1/2” plus 4 – 1/2” & 3/4”E, bottom 3 – 1/2” plus 2 – 1/2” & 3/4”E.