Steel City 521511234GB 4-Inch Square Steel Outlet Box, 21 in³, Ground Bump

It's a 4 inch square box, 1-1/2 inches deep, with 21 cubic inches of volume. That cubic-inch figure is the number you work from when you count conductors, devices, clamps and grounds for box fill, so write it on the layout rather than assuming a standard 4-square value.

The 521511234GB comes with a ground bump, the raised, tapped boss in the back of the box that takes a 10-32 green grounding screw for bonding your equipment grounding conductor. The bump is part of the box; the screw and pigtail are what you supply on the job.

At 21 cubic inches you have limited room. A single device on a mud ring plus a handful of 12 AWG conductors eats that space fast once you count the device, the clamps and the ground. If you're gang-splicing or landing more than a few circuits, step up to a deeper 4 square box, typically 2-1/8 inches deep, instead of this 1-1/2 inch version. The shallow depth is what makes it useful in a furred-out wall or shallow stud cavity where a deep box won't sit.

Not directly. A 4 square box takes a device ring (mud ring or plaster ring) to reduce the opening down to a single or two-gang device and to bring the device out flush with the finished wall. Order the ring separately and match its raise to your drywall or plaster thickness. The box itself is sold each.

Drawn. The body is formed from a single piece of steel rather than welded up from separate panels, so there are no seams at the corners. It also has a ground bump, meaning the grounding screw provision is formed into the box back instead of relying on a loose clip.

Yes, the 4 x 4 inch face is the standard 4 square footprint, so device rings, covers and bracket accessories sized for 4 square will land on it. The only thing that changes between it and the rest of your stock is depth, 1-1/2 inches here, and therefore the 21 cubic inch capacity.

Manufacturer part number 521511234GB from Steel City. Steel body in a silver finish, which on a drawn steel box is the bare galvanized surface rather than a painted coat.