This is an incredibly affordable doweling jig for woodworkers who want a quick joint without a lot of fussy layout. Many doweling jigs require that you make a mark on the inside edge of the joint, meaning you either have to transfer marks from the face to the edge, or measure and mark with a tape measure. Since this jig is transparent, layout is much simpler. Just set the two parts together and strike a line across the center of the joint. The see-through reference lines allows you to line up the jig perfectly. Clamp it in place, drill and you’re done! Hardened steel drill guide will endure years of abuse. Holes are spaced 3/4″ on center. Convenient hanging hole. Precise centerline for the joint, plus center lines for two dowels. Measures 2″ x 4-1/2″. Drill guide is 3/4″ thick, perfect for 3/4″ face frames.