I use a similar model made by Behringer http://www.behringer.com/EN/Products/CT100.aspx
For the money this is the best product for testing cables it does everything and provides a 1k test tone for checking inputs. Its a great unit that everyone should own.
Totally agree. It's the #1 thing they makes for taper use. I don't keep one in my recording bag, but I keep one with my recording stuff at home and throw it in the car to bring along to fests. It is a invaluable stress reliever for very quickly chasing intermittant cable faults or simply confirming that your cables are in good shape. Plug 'em in, confirm good wiring on all lights, push the intermitant test button, wiggle them around and see if any light pops back on to find even a very quick intermittant fault. 15 seconds, done, total peace of mind.
I bought one years ago as a cheap test tone generator to match levels and calibrate meters. It is switchable between 1k and something lower, 440k or 700ish maybe, can't recall. Works great for that, but it is the easy cable testing that totally rocks.