Sioux Valve Seat Grinder Stone Holder and Star Drive with 2 Pilots and 6 Stones Product Specifications: Sioux and Star Drive Valve Seat Grinder Mount with 2 Pilots and 6 Stones Robust Sioux Style Valve Seat Grinder Holder 1 1/16" Thread. + 2 pilots (pilot measurements: 5/16" and 1 1/32") + star drive cone + 6 stones 2 1/4" 2" 1 7/8" 1 3/4" 1 5/8" 1 1/2".
