Just received my 24mm from Keh and according to the description, it is supposed to be an Ai lens (converted by Nikon). When the lens came, the prong is the Non Ai prong. From the ridge, it does look like it has been converted but I just want to make sure that it is. Hope you guys can help. Thanks! I did mount it successfully on my FM2n and D70s; the lens mounted without a hitch.