The jimmy jig/ used 1/2in ply cover with laminate both sides, hardwood telescoped rails, or 20/80 aluminium extrusions and a clamp that forces the jig rails against the frame that surrounds the table saw/ rock solid, the fence will never deviate from parallel as it it fixed to the sliding platform, In the unique aperture of the jig you can add a router or jig saw in an extra insert, these inserts are also a zero clearance over the blade