Fowler 52-223 series metric digit micrometer has a choice of measuring range and a flat anvil/spindle pair with a 6.5mm diameter measuring face for general purpose measuring. The digit display has 0.01mm graduation intervals and an accuracy of 0.001mm for precise readings. Micrometers up to 100mm have a secondary Vernier scale with 0.001mm graduation intervals and an accuracy of 0.001mm and microfine graduations on a satin chrome finish to provide clear reading. The positive locking nut on the spindle locks measurements in place for accurate readings. A zero adjustment on the sleeve ensures accurate measurements. The anvil/spindle pair have hardened, precision-ground, and micro-lapped measuring faces with 0.00076mm flatness and 0.001mm parallelism on 0 to 25mm micrometers to provide accurate measurements. The spindle thread is hardened, ground, and lapped to provide smooth movement, accuracy, and long life. The ratchet-stop thimble provides an audible sound and stops turning when the spindle comes into contact with the workpiece, providing constant force for consistent measurements between operators. The blue baked-enamel frame provides durability. The insulated steel frame helps reduce temperature-related expansion or contraction providing for accurate measurements. The micrometer includes a wrench and fitted case. Micrometers 50mm and above include a standard. SpecificationsDisplay type Digit with Vernier Anvil/spindle style Flat Measuring range Varies Digit graduation interval 0.01mm Vernier graduation interval 0.001mm (on 0 to 100mm micrometers) Accuracy 0.001mm Thimble style Ratchet stop Anvil/spindle diameter 6.5mm Flatness 0.00076mm Parallelism 0.001mm on 0 to 25mm micrometersMicrometers are precision measuring instruments that use a calibrated screw to measure distances. These measurements are translated into large rotations of the screw that are then able to be read from a scale or a dial. Micrometers are typically used in manufacturing, machining, and mechanical engineering. There are three types of micrometer: outside, inside, and depth. Outside micrometers may also be called micrometer calipers, and are used to measure the length, width, or outside diameter of an object. Inside micrometers are typically used to measure interior diameter, as in a hole. Depth micrometers measure the height, or depth, of any shape that has a step, groove, or slot.The Fred V. Fowler Company manufactures inspection and measurement instruments such as electronic indicators, calipers, bore gages, and digital scales. The company, founded in 1946, is headquartered in Newton, MA.What’s in the Box?Fowler 52-223 Series premium outside digit micrometer Standard (for sizes 50mm and above)Wrench Fitted case