LAN cable Modular jack RJ11+RJ45 Cable tester This product allows you to test the continuity of LAN cables and modular jacks. With this product, you can check if the LAN crimping is normal, if there are any connection errors, or if there are any disconnections. Even those without LAN cable skills can perform basic LAN cable testing at home or in the office, leading to the quick resolution of problems. How to use: Attach it to both ends of the LAN cable and modular jack. If all the lights illuminate in order, 12345678G, in a rhythmic sequence, it is normal. If there is a break, some lights will not illuminate. If the illumination order is different, such as 13245678, it indicates a connection error between pins 2 and 3 during crimping. Modular jacks use two or eight pins, but only the number of pins used will light up, which is not a malfunction. I found a new, unused one in my toolbox, so I am offering it for sale. Although it is unused, it has some minor scratches from being stored at home, which is normal for a tool. Please consider this carefully before bidding if you are looking for a perfect item. Thank you.