This stainless steel flanged insert provides a durable and precise center position when setting-up for cutting repetetive radii...e.g. curved door and window casings, cabinet bonnets, curved components for shelving units, mirror frames, etc. See the large radii set-up photos on the Circle Jig page.

It fits comfortably into a 1/4" hole and eliminates any wear factor to the pilot hole that might compromise results.