This is a Loftech TS-1 signal generator. A little used, missing knob cover on the frequency knob. Very versatile unit and rugged. Holds it's calibration pretty well. This is an older unit. There are newer ones and rack mount versions also.
In this video I'm running right into a speaker cabinet. Using a small power amp you can just about test any speaker combination. Great for testing crossover points, finding defective horns and speakers.
Great tool for testing frequency response on rack gear.
You see these units from time to time on the net at great prices. If you get the chance to buy one you won't regret it. If you can't find one, I would recommend getting a generator with a variable frequency knob instead of incremental switches.
One place you can't skimp is your test equipment. Make sure whatever signal generator you get gives you a rock solid perfect sine wave on your scope.