The Fowler 52-215-006-1 vernier micrometer set has six micrometers with a 0 to 6" measuring range and a 0.256" diameter flat anvil/spindle pair for general purpose measuring. The Vernier scale has 0.0001" graduation intervals and 0.00016" accuracy (up to 2") for precise and accurate readings. The anvil/spindle have hardened, precision-ground, and micro-lapped carbide measuring faces with 0.00003" flatness and 0.00005" parallelism for accurate measurements. The positive locking lever on the spindle locks measurements in place for accurate readings and the zero adjustment on the sleeve ensures accurate measurements. Friction and ratchet style thimbles apply constant measuring force for repeatability between users. Friction-style thimbles are suitable for one-handed operation and stop turning when the spindle comes into contact with the workpiece, providing constant force for consistent measurements between operators. The ratchet-stop thimble provides an audible sound and stops the spindle from turning when the spindle comes into contact with the workpiece, providing constant force for consistent measurements between operators. A satin chrome finish on the thimble and sleeve helps reduce rust and glare, providing long life, and microfine graduations help ensure accurate readings. The set includes six micrometers with 0 to 1", 1 to 2", 2 to 3", 3 to 4", 4 to 5", and 5 to 6" measuring range; 1", 2", 3", 4", and 5" standards, wrenches, and a fitted case. Micrometers 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 on a scale . 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 measuring instruments such as electronic indicators, calipers, bore gages, and micrometers. The company, founded in 1946, is headquartered in Canton, MA.