Doweling jig. A precision jig that assures accurate line up of dowel holes in furniture and carpentry. Clamps onto work from 0" to 4" in width. Revolving turret has 6 twist drill sizes, 3/16", 1/4", 5/16", 3/8", 7/16", and 1/2". Dowel Size: 3/16" to 1/2"