Easily and quickly test your network cabling for connection problems (i.e. broken wires) and for correct ordering (just in case the wires have been crimped in the wrong order). RJ45 sockets - will test any cabling that uses RJ45 ends including CAT-5 CAT-5E and CAT-6. RJ11 sockets - will test any cabling that uses RJ11 ends including ADSL cables. Useful for anyone making their own cables or fitting network cable into the face plates etc. Needs 1 x 9v PP3 battery which is supplied