4” pre-galvanized steel square box, 1-1/2” deep, 21 cubic inches. Welded construction, 1/2” & 3/4” eccentric knockouts and “SV” 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.