2-7/8" (73MM) Flex Hone 240 Grit Aluminum Oxide Designed to work with Nikasil coated cylinders with bores from 2.55" to 2.900 Designed to work with Nikasil coated cylinders with bores from 2.55" to 2.900". Tool is self centering and is easy to use Made in USA by the one of the best cylinder hone manufacturers, FLEX-HONE. Tool is labeled as 2 7/8" diameter but is actually slightly large to apply the required wall force for a 2 7/8" cylinder bore