Kreg's Blank Router Table Insert Plate is a rugged 3/8" thick (9.5mm) phenolic plate. The phenolic plate will handle most commercially available routers, simple drill the appropriate hole using the drill guide that is engraved on the underneath side to get the bit centred in to hole, especially if using a guide bush.
The Level-Loc Reducing Rings are changed with different diameter bits to minimise the gap around bit and assisiting with dust control. The plate comes with three Level-Loc Rings: 25mm, 30mm for use with universal-style guide bushings, and 67mm.