9-Inch by 12-Inch by 3/8-Inch router table insert accommodates heavy routers. Snap out rings of 3-7/8-Inch, 2-5/8-Inch and 1-1/4-Inch for small cutters and Porter Cable template guides. Shoulder pin for freehand work. Although not required, for easier installation see Big Horn No. 18120 installation template.