Scott M. Knowles , Mar 14, 2007; 08:41 a.m.
I use one with a macro lenses in the field if I don't take the AB III (new). It's only problem is with some lenses that rub against the rail when mounted in line with the rail (over the hot shoe). This is overcome with a washer or something similar (low profile panorama head) between the rail and camera body. The one in your photo is missing the end tab which connects it to the bellows set if you have or acquire one. It's an easy piece to lose and hard to find, so you might ask the seller because they usually come with the rail. Good luck.