Recently in another thread someone asked about the difference between Black VS Touch and other versions. I hadn't been able to provide a proper reply at the time because I had just switched to a different version of VS. After more playing time I can provide additional feedback but don't remember in which thread that was, thus this new thread. I'm finding the Tonic+ Longevity is providing more control than Black VS Touch but is still playing more comfortably. I have no idea why this would be. I do know that color pigments can effect playability. The fellow who owns G&G said that he and his playtesters test different colors and he won't carry colors in a given string if they play too differently from the majority. Maybe the Black plays less comfortably/stiffer due to the color treatment but less consistently due to its thinner gauge while the Longevity plays more comfortably while still providing increased accuracy due to its thicker gauge. I have no idea and have long since learned that numbers can only be used as a broad reference point for stringing and the thing that matters most is how they perform on the court. In this case I'm really enjoying Longevity over Touch for whatever reason and will be trying the new 15L VS Touch when its time to restring (Longevity is really thick and supposedly less consistent in gauge being advertised as >1.35).