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.