Greenlee 60078 .500-inch diameter X .469-inch, flat D shaped replacement punch to be used with the knockout unit 60077, sold separately.
From the Manufacturer
Knockout punch, D-shaped, punch size 0.500 x 0.469-Inch. Hole size 0.500 x 0.469-Inch. Maximum capacity mild steel 16 gauge. Centering marks For hole alignment. For installation of switches or instruments. Use with manual wrench or hydraulic driver.
