Air Capital Microstop and Countersink Kit features a microstop which allows precise drilling of countersink hole for flush-mounting rivets. Countersinks screw into microstop, which has 1/4in. shaft and adjusts in 0.0001in. increments, for countersinks and rivets at an optimum chosen depth. Application Microstop and countersink. Microstop has a nylon tip to reduce damage to sheet metal Rated for 3000 RPM Has 5/8in. cutter capacity Accepts standard 1/4in.-28 threaded countersinks Includes 3/32in., 1/8in., 5/32in., 3/16in. and 1/4in. 100 countersinks