Purchased 3-4 years ago, and have been partially used. The yellow-packaged roto yellows strings are missing the 4th string. There are 5 SIT strings remaining, which are thin, and probably the size indicated on the package, but I can't tell by looking at them. Would these be suitable as spare strings? They aren't obviously rusty, but they aren't like new either. Please refrain from purchasing if you are overly concerned about condition. I am also listing these on other sites, so I may suddenly remove the listing. Also, please understand that if they sell on another site first, I will cancel the purchase made here.