This laser calibrator is made of high-grade aluminum alloy, offering lightweight construction, high strength, corrosion resistance, and long service life. It includes a complete set of accessories for immediate use upon arrival. Features: - Constructed from high-grade aluminum alloy for durability and reliability. - Infrared laser provides bright, clear, long-distance visibility for precise calibration. - High-precision, adjustment-free design enables convenient and accurate alignment. - Streamlined battery compartment with screw-off tail cap for easy access and practical operation. Usage Instructions: 1. Measure the inner diameter of the tube and select the appropriate adapter (eight small black caps included). 2. Use a cross-head screwdriver to attach the adapter to the calibrator’s tail. 3. Ensure the calibrator body remains straight by fully tightening both the battery compartment and switch housing. 4. Secure the adapter and insert the tail tube into the target tube, ensuring the switch faces upward during insertion. Mount the device and align using a sight or optical scope. 5. Adjust the sight or scope until the laser dot is parallel to the reference line for accurate calibration.