Greenlee 1577 PC Cable-Check Pro PC/LAN/Phone Patch Cable Tester Rugged case with built-in handle for easy transport This new universal tester maps cables, detects good connections, opens, shorts or crosses PC Cable Check Pro is a universal tester for all computer cables. A true cable mapper, it will quickly & easily troubleshoot or map cable pin-out. Features easy to read & understand with LED indicator lights plus battery saving automatic shut-off. 9-Volt battery included. Test 50 ohm cables up to 1000' (305 m) and 75 ohm cables up to 600-Feet (183 m).