We find it amusing that many sell this as a KGB monocular, giving all sorts of stories about how they were used by the KGB for clandestine surveillance. Maybe some were used for that purpose, but it is really just an excellent, and very high quality, monocular. With the ring placed over the middle finger, and the instrument grasped in the fist, you can get a very, very steady image. The length is only 1.5 inches.
All optics are glass, and it actually uses roof prisms to get the small size.
Also, it focuses as close as 1.5 feet, at which point it is a magnifier. Some ask what use a monocular with such low power can be. Actually higher power magnification is rarely needed. We sold many of these to deer hunters who wanted to know if that brown thing at 100 yards was a deer or a brown bush. And you can tell the markings on a warbler at 30 feet.