Greenlee 77U-1/2 Slug-Buster Self Centering Knockout Punch Unit for 1/2-Inch Conduit Self-centering punch aligns itself on pilot hole No need to draw crosshairs or line up die alignment marks Unique punch also splits slugs for easier slug removal Use with battery-powered, hydraulic, ratchet or manual drivers Punch unit sets include punch, die, and draw stud