Just curious more than anything but...... What is the difference between normal NXT string and string labelled as "NXT demo string, not for resale" or something like that? It's actually written on the string. I ask because I was demoing a couple frames from my local shop and all the demos are strung with the "Demo" string. I knew they always used NXT for demos but have never seen it actually labelled as "Demo" string. I know many Prince Demo racquets actually have Demo stamped on them. From what I am told, no difference in the frames. Just wondering if there is any difference the string.