Product Details - Routing - Router Tables & Accessories - Router Insert Plate - Acrylic

It includes four magnets which are supposed to be set into the corners of the recess cut into the table top. The grub screws in each corner are attracted to the magnets and allow for micro adjustment of the plate to ensure it is even on all four corners. The included insert rings have 30mm & 65mm holes for most standard bits, but can be removed completely, providing a 91mm hole for the largest router bits.

Also included is a starter pin that you can use to pivot the work piece into the router bit, reducing the chance of kickback when freehand routing.

To mount your router onto this plate, remove your current plastic base plate, mark the points where that base attaches to the metal base of the router, drill the holes and then screw through the top of this plate into the metal base of the router. Because the plate is made of acrylic, you can use standard drill bits to tap these holes.