Greenlee Bushing Universal Stud 712C Bushings for pre-punched hole or 1-11/32" (34.1 mm) diameter hole punched by 710 Metal Stud Punch Helps protect wire insulation from sharp edges of metal studs Makes pulling smooth and easy by preventing hang-ups of cable on raw metal edges Locks securely into metal studs from 24 gauge to 12 gauge (0.6 mm to 2.5 mm)