1Dial: dial calibration clear, exquisite workmanship, two-way shock, more intuitive reading. 2Measuring claw: The side head is made of stainless steel, not easy to wear, fine workmanship, durable. 3Tightening screw: Adjust the elastic degree of fastening screw fixing steel sheet, humanized design, easy to operate. 4Fine-tuning roller: Adopt roller design, thumb support, more comfortable and convenient to use. 5Multi-function: can measure outside diameter, inside diameter, hole depth and step size.