Updated design has hardened steel adapter with 5/16 set screw so you use the same shop smith hex wrench on this adapter as your other Shop Smith adapters. Larger face plate give better support to larger boards. Ring Master Arbor for Shop Smith. Features a 5/8″ hole with set screws, 1/2-13 stud. Use for attaching board to lathe when using the Ring Master to make wooden bowls.