Features: 1Strong Material: The main body is made of aluminum alloy with anodized surface, which reduces the weight while having strong hardness. 2Accurate and Scratch Proof: Stainless steel calibration clear on measuring rod for accurate measurement, rubber ring at both ends, used to adjust and fix the measuring rod, and the contact surface of the ring is wrapped with rubber ring to avoid scratching the ring. 3Deviation Measurement: Rotate the lock handle, adjust the measuring rod, lock the sliding sleeve, adjust the distance between the measuring rod and the ring, determine the value of the measuring rod, measure the deviation between the tail hook and the ring. 4360 Rotary Correction: Rotate the spacing between the wheel group and the tail, 360 rotation measures the spacing between the wheel group and the tail. Lock the rod, accurate thread, closely fit, clockwise rotate the handle, screw the rotary rod into the tail, accurate lock. 5Usage Indicator: Hold the frame in one hand, keep the body steady, one hand open or push the main body (specifically according to the tail hook), adjust the data deviation of the measurement rod corresponding to the data deviation of the ABCD point is OK, the adjustment process may need more subtract. (Note: ABCD refers to 4 points of the end face of the rim) Package included: 1 x Main Rod1 x Rotary Rod1 x Rotary Handle1 x Black Measuring Rod1 x Silver Measuring Rod&nbsp&nbsp 1 x Lock&nbspHandle