Mahr MarCal 16 FN 4100420 Vernier Caliper is mainly used to measure the diameter of circular objects. It has got circular jaws that fit perfectly on the circumference of round objects. It consists of two scales, the main scale which is fixed, and a moving scale. With the help of the two scales, the accurate dimension of the object is measured. Mahr MarCal 16 FN 4100420 Vernier Caliper is easy to use and maintain. It can be purchased from us at a budget-friendly price.