Conduit wiring system. Installed in ceilings or walls for lighting fixtures, switches or receptacles. Used where multiple conductor runs are split into two or more directions to bring power to a number of electrical devices. Drawn construction and raised grounding provision for surface mount applications in ceilings or walls for lighting fixtures or receptacles. Eight 1/2"and four 3/4" conduit knockouts (sides). Two 1/2" and two 3/4" conduit knockouts (bottom). 4" square x 1-1/2" deep - 21.0 cubic inches. Acceptable for use in 2-hour rated fire walls. UL Listed. UPC bar code.