I've used each of these for about a year, but since I bought them all here, I don't know the exact usage period. I was using them normally until recently, so I don't think there are any problems with their use, but I'm listing them for sale when the strings break. The racket with strings has Nanogy 95 strung at 28 pounds, but I think it's a little loose now. I can cut the strings before shipping if you'd like. Also, I can remove the grip tape before shipping if you request it. I'd prefer not to sell them individually, but if you really want to, I'd consider it for around 20,000 yen.