device also measures the length of the arch, or the distance between the heel and the ball (metatarsal head) of the foot. For this measurement, the device has a shorter scale at the instep of the foot with an indicator that slides into position. If this scale indicates a larger size, it is taken in place of the foot's length to ensure proper fitting. For children's sizes, additional wiggle room is added to allow for growth. The device also measures the width of the foot and assigns it designations of AAA, AA, A, B, C, D, E, EE, or EEE. The widths are inches apart and differ by shoe length. Some shoe stores and medical professionals use optical 3D surface scanners to precisely measure the length and width of both feet and recommend the appropriate shoe model and size. Conversion between US and UK sizing Continental Europe In the Continental European system, the shoe size is the length of the last, expressed in Paris points or , for both sexes and for adults and children alike. Note that the last is typically longer than the foot heel to toe length by to , or 2 to Paris points, so to determine the shoe size based on actual foot length one must add 2 Paris points. Because a Paris point is of a centimetre, the formula is as follows: equivalent to: . The Continental European system is used in Austria, Belgium, Denmark, France, Germany, Italy, Luxembourg, the Netherlands, Norway, Poland, Portugal, Spain, Sweden, Switzerland, and most other continental European countries. It is also used in Middle Eastern countries (such as Iran), Brazil—which uses the same method but subtracts 2 from the final result, in effect measuring foot size instead of last size—and, commonly, Hong Kong. The system is sometimes described as Stich size (from Pariser Stich, the German name for the Paris point), or size (from a German name of a micrometer for internal measurements). Mondopoint The Mondopoint shoe length system is widely used in the sports industry to size athletic shoes, ski boots, skates, and pointe ballet shoes; it was also adopted as the primary shoe sizing system in the Soviet Union, Russia, East Germany, China, Japan, Taiwan, and South Korea, and as an optional system in the United Kingdom, India, Mexico, and European countries. The Mondopoint system is also used by NATO and other military services. The Mondopoint system