A gauge similar to a slide gauge, used to measure the distance between the plates of a clock or the length of a pinion from shoulder to shoulder, showing both measurements at the same time. The name is also applied to a caliper-type of instrument with legs adjusted by a nut on a screw to take pinion measurements. A further type is like a wire gauge and measures the diameter of a pinion; it is particularly useful when measuring a pinion with an odd number of leaves.