Fits Bore Sizes 4 to 4-1/4,This 240 Grit is perfect for prepping the cylinder walls for Moly Rings!Heavy Duty Flex-Hone has 50% more Globulesthan the standard flex hone. (13 1/2OAL)This EXTREMELY POPULAR SIZE ball hone fits Common Chevy, Ford and Chrysler V-8 applications....Brush Research Mfg. Co. has a Flex-Hone For Any Type And Size of CylinderThe Flex-Hone Process (Super finishing) produces a controlled surface condition unobtainable by any other method. It involves finish, geometry and metallurgical structure. A high percentage plateau free of cut, torn and folded metal (with radiused ports).NOW is the time to order this item.