I'm way too picky, but you don't really need to say "no mint mark". They're just Philadelphia coins. You could say "1966-P", or just "1966" and Philadelphia is assumed. The reason I bring it up is that there seems to be this perception out there that "no mint mark" coins are somehow valuable, probably from YouTube videos, due to a couple valuable proof dimes that were missing the S, and I see a lot of posts lately with this "no mint mark" thing. Maybe I'm the only picky one who senses a misguided perception of "value" every time I see "no mint mark". (Am I?)