I bought this to help with post stringing and my wife's racquet. It works OK, but it is not something I would keep in my pocket for a match. I still had to do some manual straightening on my string jobs.
It works okay. The mains on my racquet are narrower than the width of each of the two "stars" that run up and down the string. While I straighten one string, the one next to the other star is pushed over alignment. As far as it straightening the crosses, it does very little to those as well. Would like to see thinner stars and more accurate advertising. Works better right after stringing vs. after a set or two of playing. If you have wider mains, it may work better for you. Used on Head Graphene Speed Pro.
The String Thing works like a charm. Every bit as useful as advertised in the online videos. Simplifies the process of straightening strings before and during changeovers so I can focus on my tennis! Thanks Midwest Sports.