CTA Tools 1139 Flex Hone - 20-Millimeters is designed to removes cut, torn and folded metal to produce long wearing surface. This tool is for use on engine and brake cylinders, hydraulics, valve guides, lifter bores, diesel cylinders, cam bearings and more. Heavy-duty construction allows for strength and durability. Whether tuning up your '68 Corvette or changing the oil on a John Deere tractor, CTA can supply you with the tools needed to do the job. California Prop 65 - Warning, This product contains chemicals known to the State of California to cause cancer, birth defects or other reproductive harm.