Critical for consistent angling success, Dr Slick's popular 4.00 inch Hook File is sturdily constructed from rugged tough stainless-steel with dual diamond grit surfaces and guide grooves to make short work of dulled hook points. Perfect for keeping your flies sharply honed and always ready for action, Dr Slick's economically priced 4.00 inch Flat Hook File is a wise buy. (Fine and Medium Grit surfaces)