Blank, 2-1/8 in D, 4 sq-in boxes are tamper and vandal-proof boxes without holes and knockouts. Garvin Industries can customize a solution by adding only the knockouts you need. They are installed in air plenum walls or ceilings for 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 multiple direction conduit runs are necessary.