I'm not entirely sure what material these are made from, but it looks and feels like stainless steel. (Excellent!). My pack contains 24, rather than 12 as stated, so more good news my way. I'm still not sure what thread type these are either, as Leo Fender was a fan of Henry Ford's production line techniques, but that was way back before international metrication. Now for the punch line: I ordered these for a Gibson Bass pickup selector, made by the Mallory Battery and Charger company and used by Gibson in the early 1970;s. Very close but not quite a standard "Chicken Head" knob.