Recommendations for a C Mount adapter on ebay?

I'm looking for recommendations for a C Mount adapter on ebay that will allow focus to infinity. I've gotten a couple of the ones that say they "focus a little beyond" infinity only to find they don't even allow for focus to infinity. They are a little bit too thick to allow my C Mount lens to focus at infinity. I even adjusted a couple of my lenses to focus at infinity with these mounts to confirm they are too thick. Can anyone recommend an adapter on ebay they've gotten that does allow for focus at infinity?