The jig requires a router fitted with a 30 mm. guide bush & 12 mm. Diameter: long reach cutter. For most common sash mortice & dead locks with up to 3 in. deep mortices & a 7/8 in. or 1 in. face plate. Deeper mortices can be achieved with a suitable size of auger bit. Also suits face plate on a 1.in mortice latch. NOTE. Use on doors 34 mm. to 58 mm. thick.