Cut flawless circles from 10'' to 52'' in diameter without complicated math equations! The Rockler Circle Cutting Jig sets up in minutes and mounts quickly to many popular routers made by Porter Cable, Makita, Hitachi, DeWalt, and Bosch. Or, easily drill your own holes to custom fit any router. Includes two center pivot pins which are used as a pivot point to rout perfectly arced circles (one pin is used for soft woods, use the other if your design allows drilling a center hole). A recessed groove in the jig lets you slide the center pivot pin (your center point) up or down the length of the jig to find the correct, exact diameter of your circle. Use the 4-star knob to tighten the T-bolt with the center pivot pin installed and you're ready to go!