The CT100 offers a very reasonably priced cable tester with good performance and functionality. The unit is robust and will stand up to the knocks it will experience in a kit bag Cable Tester: It not only performs a simple continuity test but also looks for a level of resistance between pins of more than 50k ohm (this is not documented). It also allows the physical condition of the contacts and cable to be tested by detecting (and latching) intermittent connections whilst the cables are manipulated. Test Tone: Provides 400Hz & 1kHz square wave signals at microphone and line levels ... superb for testing sound systems. Against: The instruction manual is rubbish ... OK, the functionality of the tester is simple and one can work out the LED display configurations but it would be so much better if there was some explanation, especially regarding TRS and TS leads.