The ad states these are "6K collets" which I've never heard of. Look like 5C to me. It apparently comes with a closer for a South Bend 10 inch lathe. I'd be tempted if I had a South Bend lathe.
6K-colletts - tools - by owner - sale - craigslist
6K-collet set @ hand wheel for South Bend light 10 inch lathe 1/16th-5/8 by32nd and 1/64 37 colletts mfg. by Hardinge.
madison.craigslist.org