The stair jig is made of 12mm thick High Pressure Laminate, dimensionally stable and with a lifetime guarantee never to warp. This jig's clever design means it only uses a standard 30mm diameter bush to achieve the various tread and nose sizes, eliminating the need for different sized bushes or sub-bases. The jig offers a choice of closed riser standard staircases for 22mm, 25.4mm, 28mm and 32mm tread thickness, as well as open riser stairs. On completion, the staircase will qualify within British Standard 585 Part 1, (1989) regarding wooden staircases; it will also follow the Building Regulations Approved Document K (1991). It is supplied with complete and comprehensive instructions on use and staircase design. Additional requirements include 1/2" router, 30mm guide bush, two G-clamps plus a cutter to suit your chosen tread thickness. Wedge for tread and riser requires a 3 degrees angle. The jig comes with 2 inserts allowing 4 different protrusions of nose over riser.