Exist Sharpen old 4 inch knockout set index Explosives resource
Knockout Punches
AMZCNC Hydraulic Knockout Hole Punch Driver Kit 1/2 to 4 inch Electrical Conduit Hole Cutter Set KO Tool Kit Metal Sheet Puncher (12TON(1/2"~4")) : Amazon.ca: Tools & Home Improvement
Klein Tools 53727SEN Knockout Punch Set, 3/4-Inch : Amazon.ca: Tools & Home Improvement
Knockout Punch Set, 3/4-Inch - 53727SEN | Klein Tools
154 1/2" - 4" Standard Hydraulic Knockout Set - Current Tools
Knockout Punch Set (3", 3-1/2", 4") for use with 902-545