If your cassette deck sounds great when playing its owntapes but sounds muffled or unclear when playing tapes made on other machines, it'slikely that the record/play head(s) are out of alignment.With the use of this special azimuth alignment cassette youcan quickly and accurately re-align your deck’s head(s). Best of all, unlike other more expensivealignment cassettes, no expensive test equipment is needed with the use of thiscassette. All you need is a “mono”switch on your receiver, amplifier or preamplifier. If you don’t have such a switch, you onlyneed a Y-adapter cable (not included) such as this one: http://www.amazon.com/C2G-Cables-Stereo-Female-Y-Cable/dp/B0002J1LE8/ref=sr_1_2?ie=UTF8&qid=1448639176&sr=8-2&keywords=stereo-to-mono+rca+audio+adapter The cassette is new but not sealed and it comes with step-by-step instructions.