Smart Box is like no other electrical box on the market today! The unique feature about Smart Box is the interior sidewall mounting screws. The interior mounting makes the box a great old work box. It makes no difference whether there is sheet rock, paneling, plaster, etc., on the walls, you install the box to a beam just as you would in new work construction. This makes for a strong installation at 1/3 less the cost of the traditional old work box. Good for NEW WORK and OLD WORK construction. Unmatched in VERSATILITY. Contractor FRIENDLY. Mounts to either wood or 25 gauge metal studs. Uses less shelf space in warehouse and truck.