Bore gage
A bore gage is a precision measurement tool used to determine the internal diameter, radius, or circumference of a hole, also known as a bore. Bore gages are used in multiple fields of mechanics and come in a variety of types, used for different purposes when considering the job at hand and the preference of the user. The different varieties of bore gage include: telescopic bore gage, small hole bore gage, beam bore gage, and dial bore gage. Telescopic, small hole, and beam bore gages all involve a transfer process to get a final measurement, whereas a dial bore gage measures a bore directly. Small hole bore gages come in the full-ball or half-ball variety. Dial bore gages also come in electronic or wireless versions, which can be used to get an even higher level of precision and accuracy.