Quickly identifies fitting thread patterns for every common standard, metric, and British thread grease fitting. Thread pitches include NPT, Metric, UNF, BSW, BSF, and BSPT. Made in the USA from high-strength aircraft grade aluminum alloy. How To Use: Thread the fitting your trying to identify into one of the holes on the tool that looks correct to the eye. If the fitting will not thread in correctly try the next hole size up or down until the correct fit is found. Each thread size and type are etched on the grease fitting thread tool