Sony with the exclusive Super Performance Mechanism, to give you greater performance in recording and repetition.
We have applied to each of our tape cassettes the new exclusive tape transport mechanism, which we have called the Super Performance Mechanism.
Because that's exactly what you get. You already know that it doesn't matter how good the quality of the tape is. You will not receive the full benefit unless it is transported by your recorder heads in a smooth and accurate manner. Our SP Mechanism solves this problem in a wonderful way, giving you a notable gain in sound uniformity But that's not all; the tapes are characterized by new formulations of magnetic materials that satisfy special recording/replay needs. So whatever you want to do, it will sound better than ever. Add to this a high-precision case, larger sight glasses, and a larger, two-sided index sheet, and you'll understand why we say "Brand new."

Sony patented it as SP-Mechanism and later developed it into SP-II.