Features High quality durable stainless steel material: the main body of the micrometer is made of stainless steel with chrome plated surface, wear-resistant and durable ALLOY MEASURING HEADS High quality alloy measuring heads can be used for various internal size measurements, fine workmanship and no burr. Precise Measurement The precise machine structure is equipped with a locking device, making reading more intuitive and convenient. Easy to read marking line: clear laser marking line for convenient reading. ACCURATE REPEATING MEASUREMENTS The integrated ratchet stop device ensures accurate, repetitive readings. Specifications: Type: Internal Micrometer Measuring range: 5 mm ~ 30 mm. Material: stainless steel. Precision: 0.01 mm. Weight: approx. 268 g. Zero settings: Clean the surface of the measuring anvil heads with a soft cloth and then turn the gauge to contact two measuring surfaces. If the two zero lines of the differential sleeve and the fixed barrel do not match, use the following two methods to adjust. Method I:If the error is less than 0.001\" (0.02mm), use the ratchet stop to tighten the screw, and then use the wrench to tighten the fixed barrel until two zero lines are aligned. Method II, if the error is greater than 0.02 mm (0.001 inches), Step 1: Tighten the screw with the ratchet stop, then loosen the ratchet stop with a wrench and remove the differential sleeve. Step 2: Re-align the zero lines of the fixed barrel and differential sleeve, and then put the ratchet stop back in. Adjust it again with Method I if necessary. Note: Under normal use, the micrometer does not need to be calibrated. Micrometers only need to be calibrated when they are severely worn. Package includes: 1 x internal micrometer. 1 x wrench. 1 x calibration ring. 1 x packaging box. Note: Please note that the new and old type of this product will be sent at random. Please make sure you do not mind before ordering. Package List