1-1/2" deep, 4" square drawn junction boxes with Chicago plenum (8) 3/4" side and (2) 1/2" & (2) 3/4" bottom knockouts that are "air tight" for 3/4" conduit runs. These boxes are used in air plenum wall or ceiling surfaces to install lighting fixtures, switches, receptacles or other outlet devices. Square boxes are used to bring power to a number of electrical devices where multiple conductor runs are split in two or more directions. Garvin Industries’ 4S Boxes can be surface or flush mounted when multi directional conduit runs are necessary. They include a raised ground provision on the bottom of box.