This is a pretty special lens and I would definitely keep it if I still had my OM gear. Really fast for its era and super sharp.  I bought it here a few years ago with the dented filter ring and all, which we all know happens when your camera is handing from a strap and you accidentally swing it into something. Fortunately the original owner did not do anything to hurt the optics or mechanical functioning. Aside from the filter dent, it's nearly perfect. Glass is clean (and perfectly aligned!) and the aperture and focus rings work perfectly. I will list it for less that the median sales price because of the ding, but know you will be getting a great bargain!