This listing is for one set of six (6) Single line Kluson's from a 1961 Duo Sonic. Will also fit Musicmaster's. The nickel plate is oxidized. Some turn smooth, some are a little loose, but not skipping.  I suspect by the differing patina on the buttons, this guitar had a couple changed along the way. Good, solid original buttons. However, they are what they are, old Kluson's. They were made to much sloppier tolerances than what we see today and on top of that, they have over 60 years of use and abuse on them. For that reason, they are sold as is. No mounting hardware included.