The Brown & Sharpe 599-815-4 spring caliper has a 4"/100mm maximum distance for use in measuring inside dimensions. It has hardened and tempered steel joints, spring, washers, and divider points for durability. The spring caliper has a knurled nut for adjusting caliper point width, and is suitable for applications such as measuring the bore of machined parts.

Calipers measure the distance between two opposing sides of an object. They make inside, outside, depth, or step measurements, according to their type. Calipers are commonly used in architecture, metalworking, mechanical engineering, and machining. The simplest calipers have two legs to mark the two points and require a ruler to take the measurement. More complex calipers use two sets of jaws instead of legs and have up to two graduated scales. Vernier, dial, and digital calipers give direct and accurate readings and are functionally identical, having a calibrated scale with a fixed jaw, and another jaw with a movable pointer that slides along the scale. The vernier caliper has a scale sliding parallel to the main scale for an additional, fractional reading to improve measurement precision. The dial caliper has a circular dial with a pointer on a toothed gear rack replacing the second vernier scale. As with the vernier, this second measurement is added to the reading from the main scale to obtain the result. The digital caliper takes a differential by zeroing the display at any point along the slide, with an LCD that displays a single value in English and/or metric units.

Brown & Sharpe manufactures precision measuring equipment and metrology hand tools. The company, founded in 1833, is headquartered in North Kingstown, RI.