Drywall Mounting Bracket Box Extender Single or Double Gang X-LargeSome items may require minimum order quantities, which can be changed in your shopping cart. Description Drywall Mounting Bracket Box Extender Our Drywall Mounting Box Extenders set back metal or non metallic electrical boxes up to 1 1 2 inches. This product works with most steel and non metallic outlet boxes, providing a level, fully supported wiring device that's flush with the wall surface. In steel boxes, they prevent arcing and shorting by