It's the same racquet I use. I replaced my old Ki5x with it. The Ki5 320 is stiffer than the older model, but it's still very arm friendly. I don't care if it feels stiff as long as it doesn't hurt my arm. I use a hybrid with Ashaway Mongut ZX 16g mains and a 16g synthetic gut cross at (54/50). Right now my favorite cross is Babolat Origin, but you can use a cheaper string if you like. Only caveat is the Monogut ZX should either be prestretched or stretched fully on each pull. If you take your racquet to a typical stringer who wants to get it done in 15 minutes (most jobs in the least amount of time) that's not going to happen. So if that's not a possibility, you can go with a good multifilament string like Prince Premier Control or Dunlop DNA at say 54 pounds. I'm assuming you want an arm friendly string. If you prefer poly, go ahead and do it, but make sure you cut it before it dies. Even this racquet won't protect you from dead poly.