Which micrometer type is used to measure holes or recesses?

The depth micrometer is specifically designed for measuring the depth of holes, recesses, or slots. It features a depth rod that extends down into the hole, providing a precise measurement of how deep the recess is. This type of micrometer allows the user to accurately gauge depths that cannot be measured using standard outside micrometers because it is equipped to reach into cavities and provide a clear reading of depth.

Other micrometer types serve different purposes. Outside micrometers are primarily used for measuring the external dimensions of objects. Blade micrometers are utilized for measuring narrow slots or grooves, making them effective but not ideal for general hole measurements. Vernier micrometers, while precise, are generally used for more specialized measurement tasks rather than specific hole dimensions. Thus, the depth micrometer is the most suitable choice for measuring holes or recesses due to its design and purpose.