# What is a small-hole gauge used for?

Measuring the inside of holes that are too small for an inside micrometer

Explanation

A small-hole gauge is used for measuring the inside of holes that are too small for an inside micrometer. A small-hole gauge (also called bore gauge) is an adjustable sphere that is placed in a small hole then expanded until it fills the diameter of the space to be measured. It is then removed and its diameter is measured using a micrometer or caliper.