Essential for measuring cross arch width interorally or on your study casts. Easy to use, sturdy, and dependable. The slide moves smoothly and easily, yet hold its position when released to maintain accurate measurements. The tips are curved and precision shaped to confidently locate and hold points for measurement. The front and back are marked with scales; both marked in millimeters up to 80mm, with large marks and numbers to denote every 10 millimeters.