Pit Posse 4 Piece Metric Stud Puller Socket Kit used to install and remove engine studs. Includes 6mm, 8mm, 10mm and 12mm fractional stud puller sockets that grab the bolt below the threads, preventing damage. It can also be used with 5/16″, 3/8″ and 7/16″ studs. For use with socket driver or 21mm box/open end wrench. Packaged in a durable molded carry case.