Features High quality alloy measuring heads can be used for various internal size measurement, fine workmanship and no burr. This inside micrometer built-in ratchet stop device ensures accurate repetitive readings. The internal micrometer is designed with locking device, precise machinery structure make it more intuitive and convenient to read. Clear marking line for convenient reading. The main micrometer body is made of stainless steel with chrome plated surface, wear-resisting and durable. Features: High quality alloy measuring heads can be used for various internal size measurement, fine workmanship and no burr. This inside micrometer built-in ratchet stop device ensures accurate repetitive readings. The internal micrometer is designed with locking device, precise machinery structure make it more intuitive and convenient to read. Clear marking line for convenient reading. The main micrometer body is made of stainless steel with chrome plated surface, wear-resisting and durable. Specifications: Type: Inside micrometer Measuring Range: 5mm~30mm Material: Stainless steel Precision: 0.01mm Weight: 268g(approx.) Zeroing: Clean the surface of measuring anvil heads with a soft cloth, then rotate measuring device to make two measuring surface contact. If two zero lines of differential sleeve and fixed barrel do not alignment, use the following two methods to adjust. Method I, if the error is less than 0.02mm (0.001"), use ratchet stop to lock screw tightly, then use wrench to pull fixed barrel till two zero lines alignment. Method II, if the error is greater than 0.02mm (0.001 "), Package Includes: 1 x Inside Micrometer 1 x Wrench 1 x Calibration Ring 1 x Packing Box Package List