M12 to CS Mount AdapterGot an M12 lens that wont focus? Some M12 lenses have a back focal length thats longer than the M12 socket built into the Ribcage. Our M12 to CS adapter threads into the CS Mount ring on your Ribcage to give you all the added flange distance youll need to focus any M12 lens that needs more room. Lock your focus in with the included locking nut. Fine tune your focus with the adjustable flange distance on your Ribcage! Have a few lenses? Buy an adapter