Hi Matt. Pleased with the binoviewer i bought from you. I noticed that it doesn't like tapered undercuts at shorter focal length eyepieces. I have managed to solve the problem by placing orings at the top of the barrels so that the retaining rings in the bino dont fall into the undercuts. On some of my eyepiece pairs i was able to reverse the barrels so that the undercut is at the bottom. Your 12 sw pair could be a possibility if the barrels can unscrew and can be reversed.
