Switch on the power on the main tester. Test of the RJ45 RJ11 Cat-5 Cat-6 cable:if all the cables work ,the lights will become green from NO.1&2 to NO.7&8 sequently.if any light is not on or turns on unsequently,the cables are broken. Automatically scan mode, rapidly testing, the streamline shape is in accordance with the design of somatology Durable design, working well even in construction location. Super handy device ensures your good mood Cable Tester for RJ11, RJ45, 10/100 Base-T and telephone cable … etc Automatic efficient scan for the miss wiring, disorder cable, open and short circuit Grounding test available Remotely test cable up to 1000 ft in length ( remote kit included ) 9 LEDs to indicate which wire whether open or not on both remote and master unit Powered by 2 pcs AAA batteries (not included) Protective power switch for low power consumption High quality soft leather case provides more secure protection