Inside Micrometer Hole Hole Inner Diameter Gage Measuring Tool 5-30mm Range 0.01mm PrecisionFeatures:High quality alloy measuring heads can be used for various internal size measurement, good workmanship and burr-free. Clear the marking line for comfortable reading. The main body of the micrometer is made of stainless steel with chrome plated surface, wear-resistant and durable. Designed with locking device, precise machine design make it more intuitive and convenient to read. Built-in ratchet device provides accurate, repeatable readings. Specifications:Type: Inside Micrometer Measuring Range: 5mm - 30mm Material: Stainless Steel Precision: 0.01mm Weight: 268g (Approx.) Ing:Clean the surface of the anvil heads with a cloth, then rotate the measuring device to get two measuring surfaces. If the two lines of the differential sleeve and the fixed barrel are not aligned, the following two adjustment methods should be used. Method I, if the error is less than 0.02mm (0.001"), use the ratchet stop to tightly lock the screw, and then use the wrench to pull the fixed barrel to align the two lines. Method II, if the error is greater than 0.02mm (0.001"),Step1, use the Ratchet Stop to lock screw tightly, then use the wrench to loosen the Ratchet Stop and remove the differential sleeve. Step 2, realign the lines of the fixed barrel and differential sleeve, then put the Ratchet stop back. If necessary, adjust it again using method I. Note: There is no need to calibrate the micrometer during common use. A micrometer only needs to be calibrated if it is severely worn. Package Included:1 x Inside Micrometer1 x Wrench1 x Calibration Ring1 x Packing Box