A vernier caliper is used to measure linear dimensions. A vervier caliper is made up of upper jaws that are used for inside measurements, lower jaws that are used for outside measurments, a lock screw, a thumb screw, a vernier scale, a main scale, and a depth rod. Very useful tools, verneir calipers come with two sets of measuring jaws that make it simple to measure either the inside or outside portion of an object. They come with both a central main scale that is fixed onto the device, as well as a vernier scale that moves along the device. The standard vernier caliper is capable of measuring to the nearest 0.001 inch. The maximum capacity on a vernier caliper is the range from the smallest value to the largest value, and typically equals the total length of the main scale.