I managed to use this set for my classic guitar for a very long time no matter I bought it very cheap here and for that reasons I was having some doubts about the quality. Normally one would change the strings set let say monthly but at times, when you're playing occasionally, don't change it so frequently ;-).
For that reason, no matter the whole set sits for long mounted on my guitar, their sound was not getting dull neither the metal covered strings rusted.
I may say you can even buy a bunch of them all thogether, always resulting in a cheap price, to allow to change them frequently for almost no money and have a very good sound and easy smooth strings to play with.
All in all I recommend those for sure. Cheers.