4-1/8" - 240 Grit. Flex-Hone tools produce a conditioned surface finish. These unique hones use a low-temperature, low pressure abrading system that produces a clean, long wearing surface. Designed to create a crosshatched surface pattern for oil retention. The silicone carbide hones are attached to flexible nylon stems that allow the hones to float, thereby assuring self-alignment to the bore. They produce a soft cutting action. Use with 10-30 wt. motor oil or honing oil (applied sparingly to bore wall). Operate hone for 10-45 seconds. Repeat until desired surface finish is achieved.