An outside micrometer is a precision measuring instrument used to measure the external dimensions of an object, such as its thickness or diameter. It consists of a U-shaped frame, a calibrated screw, and a movable spindle that can be adjusted to make contact with the object being measured. The measurement is read from a scale on the frame and a rotating thimble. Outside micrometers are commonly used in engineering and manufacturing to ensure parts meet specific tolerances. They can measure small dimensions with high accuracy, typically within a range of 0 to 25 millimeters or 0 to 1 inch, depending on the model.