This multifunction tool helps the user check sizes & threads including metric & imperial, removing the guesswork in selecting the correct size fixings. Measurements include: internal diameter of UNC & UNF nuts; diameter of metric & imperial bolts; length of rounded, pan, countersunk, set screws, together with hex head bolts; reference chart for hex cap screws. Manufactured from tough wear resistant ABS plastic. Suitable for mechanics, classic car restorers, plumbers, DIY etc.