Precise and consistent drilling depths can be achieved with these Split Ring Depth Stops. Simply slide over the appropriately sized drill bit and lock in position by tightening the socket head screw. Split ring clamping prevents damage to drill bits and allows tremendous tightening pressure so there's no slipping on the bit. Sizes include: 1/8 inch, 3/16 inch, 1/4 inch, 5/16 inch, 3/8 inch, 7/16 inch and 1/2 inch. Hex wrench included.