single blade universal hole cutter
Adjustable Hole Cutter page 167C
Single Blade Adjustable Hole Cutters are designed to cut holes and discs in mild steel, sheet metal, plastics, laminates and wood. Hole diameter can be adjusted to cut a variety of hole sizes. Maximum 3/4" cutting depth.

aka - Circle Cutters, Wheel and Circle Cutter, Universal Hole Cutter.