1/64 precision for quick and accurate outside and inside measurements Compact to easily fit in shop coat pocket Inch scale on the back of the stock allows for use as a steel rule as well Knurled thumb pieces activate the slide and allow for easy one-hand operation Straight measuring surface Description simple outside measuring while rounded nibs are used for inside and hole measurement Handy scale on the back of the stock Knurled clamp screw for easy one-hand operation A slide stop prevents tool from being disassembled Straight measuring surface for outside measuring Rounded nibs for inside or hole measurements