Has anyone seen one of these before? It came with a Zenit 3m I recently managed to get http://www.ussrphoto.com/UserContent/_G102967.JPG Looks like a flash shoe but it fits into the 3/8" tripod/ case socket under the camera.
Just maybe they used nylon to take up extra unwanted threads in bolt. Or used to hold slave flash unit. Doesen't look like it is insulating anything. Don