I absolutely love these Retro GI "Nub" thumb safeties -- and it seems George and EGW are the only ones who keep these quality parts in production and in-stock at a reasonable price. I must have these on at least a half dozen 1911s, Commanders, and 2011s!
When in the "Up" position the thumb safety locking shaft hole is not exposed to dust and dirt into the internals -- just as designed (as opposed to some other after-market brands).