This jig is made from 8 foot 2/8 framing lumber, hickory supports with carpet pad to stablize the lumber being jointed and a bridge of oak plywood that carries the router. It sits on my tablesaw. Everything must be level. There are four points on the sides of the bridge to level the path of the router. The first side of the slab musty be leveled with shims. The second side rests on the supports.