These bushings fit existing irregular shaped holes in metal studs, alleviating the need to punch holes in metal studs, weakening the structural member. Use these bushings to comply with paragraph 300.4(b)(1) of the 2017 NEC code which states that: “In both exposed and concealed locations where non-metallic-sheathed cables pass through either factory or field punched, cut, or drilled slots or holes in metal members, the cable shall be protected by bushings or grommets covering all metal edges and securely fastened in the opening prior to installation of the cable.