☛Keep your network running smoothly by testing your cables to uncover problematic shorts, open wires, crossing pairs and other wiring mishaps ☛Use for testing your homemade Ethernet patch cables to make sure they are in working order prior to connecting to your devices ☛Tests RJ45 cables, RJ11 telephone cables and network cables. Requires one 9-volt battery (not included) ☛Easy to read LED display indicates problems.Hand-held for portability. ☛If you do not like our products, we accept 30 days return and 60 days replacement, please feel free to contact us if you face any problems