A precision caliper measures linear dimensions, thickness or diameter using parallel jaws or legs. Inside, outside, dial, digital and vernier are the main types of calipers. Outside calipers offer versatility in diameter measurements, such as for pipes, while inside types can gage the distance of various openings. Vernier, dial and digital calipers utilize a calibrated scale with a fixed jaw, in combination with a second jaw and a pointer that slides along the scale. Popular digital models with data output, such as the Mitutoyo 500-506-10, support ease in measurement recording.