Works only on the head size or diameter Really only designed for measuring the head size. Not type such as metric or standard, length, thread pitch, and diameter. If you take a picture of the diameter end, then you can figure the approximate diameter. Cool tech, not really useful.
Poor Missized my bolt. 2 trips to the hardwear store.
Bolt sizer Too much room for error
Awesome Pretty neat for being done by 2 kids.