Red, 1-1/2" deep, 4" square drawn boxes with Chicago plenum (8) 1/2" & (4) 3/4" side and (3) 1/2" & (2) 3/4" bottom knockouts are used in all plenum air spaces. These boxes are used 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. They are painted red to easily distinguish them as fire alarm and life safety circuits. 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.