Which tool would you use to measure small internal dimensions with high precision?

• A. Tape measure
• B. Caliper
• C. Micrometer
• D. Ruler

Answer: (C)

When you need to measure small internal gaps with high precision, you want a tool that converts very tiny spindle movements into a readable scale with the finest resolution. A micrometer does just that with its precision screw mechanism. As you turn the thimble, the spindle advances in minute steps, and the reading on the sleeve and thimble gives you a measurement down to thousandths of an inch (or hundredths of a millimeter). That level of detail is far beyond what a ruler or tape measure provides, and it also beats typical calipers in precision for small dimensions. For true internal measurements, you’d use an inside micrometer or bore gauge, but among these options the micrometer offers the highest precision for small dimensions.