Machine valve spring seats for proper installed spring height and spring cup fitment. Cutter bodies and pilots are interchangeable, Hardened pilots fit all 3/8 and ½ hand drills. Cutter: Cuts Spring Seat .550 ID x 1.180 OD This cutter is designed for M8 cylinder heads using high lift camshafts see Feuling M8 valvespring kits #1107, 1108, 1207 Note: The M8 cylinder head material under the valvespring seat pocket to the top side of the exhaust port is fairly thin even more so on ported cylinder heads. Cutter uses the following Pilots: 9025: Fits valve guides with 5/16" - 8mm valves, EVO & TC up to 2004, EVO Sportster '86-up 9026: Fits valve guides with 7mm valves, TC 2005 and newer 9027: Fits valve guides with 3/8" valves, Pan & Shovel 1948-1983 9024: Fits valve guides with 6mm valves, M8 17 and newer 9028: Fits valve guides with 11/32 valves Note: Special Order Product only. To order please contact your MCS sales representative. / Fitment: Cuts Spring Seat .550" x 1.180"