The 712A100 - 100 Bushings for pre-punched hole or 1-11/32" (34.1 mm) diameter hole punched by 710 . Triple lock design holds bushing securely. Locks securely into metal studs from 24 gauge to 12 gauge (0.6 mm to 2.5 mm). 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.