Like new Megaperls 1.35 VF magnifier for Leica M (http://www.japanexposures.com/shop/p...96c149b5a9f6ff). It has diopter adjustment.
I almost always use wide lenses, and have never used this mag. They're about $170 new (check the website for current price in dollars). $125 or best offer delivered to continental U.S.