Properly assembled through pilot holes, they will make clean, fast and accurate holes
Detailed Description: Greenlee® Round 3-1/2-Inch conduit size knockout replacement punch is used to create 4.000-Inch diameter hole through sheet metal. It is used as a replacement on a standard round knockout punch unit. It is designed to punch through 10 gauge mild steel. Punch works using battery-power, hydraulic, ratchet or manual drivers.