1. It is an instrument used to measure the length of linear objects such as wires, cables, and water pipes. It adopts laser ranging technology and digital display technology, which can quickly and accurately measure the length of linear objects, and the data is intuitive and easy to read. 2. It is an instrument used to find network line faults and test network performance. It can detect whether the network is connected, network speed, network delay, etc., and can quickly locate the fault point. Simple operation, suitable for companies, schools, Internet cafes and other places. 3. It is an instrument for measuring optical power and distance of optical fiber. It can help users detect the transmission power and distance in the optical fiber interconnection, and it can also detect the power of the light source and the optical power after passing through the optical fiber to ensure the normal operation of the equipment. It is suitable for communication companies, banks, hospitals and other occasions that require high-quality networks. 4. The advantages include high precision, fast measurement, intuitive and easy to read, easy operation, etc., and can be applied to different fields such as electrical engineering, mechanical manufacturing, and construction engineering. 5. Features include fast fault location, multiple network test functions, graphic display, etc., and support for general network lines, including UTP, STP, FTP, etc. 6. The advantages lie in accurate measurement, multiple measurement parameters, easy operation, and suitable for different fields such as indoor and outdoor optical fiber networks. 7. In general, these three instruments are oriented to different fields and needs, and can provide fast and accurate measurement and test services, which are convenient for users to perform line detection, maintain networks or other occasions that require measurement of length, optical power and distance .