Oh shit. I think I feel triggered...They are pretty much standard fare for certain types of music in a sterile and isolated recording environment.
They are cheap, aren't going to hurt anything.... and won't put you out of tune.
I also doubt you are asking about one to cover uppoorundeveloped? technique either, but that's just my take.
They won't work for that!
For use in recording they serve a different purpose (generally) than muting with our hands to deaden strings.