Thought I'd give you guys first crack at it before it goes to ebay...
This is a Kenko 180 degree fisheye adapter. Screws onto any lens with a 55mm filter thread and turns it into a true fisheye. See below to see what it looks like installed on a Canon 50/1.4 (not included). EX condition, glass is spotless, comes with both original caps and leather hard case. On a crop frame body it will render a circular image with a 35mm lens,and a somewhat cropped circle with a 50mm lens. Price is $89.00. PM me if interested.