Found these photos on a popular auction site. What initially drew my attention is that the fixture was listed as an SL Coolbeam Zoom. Fail. But anyway, I've never seen the hunk of circular metal disc hanging off the side of the yoke. Its only purpose, the way it's installed, seems to permit a longer than stock side bolt. Is there any other function, and has anyone else seen similar? Is it an Altman part? Or a homemade locking dog, wrongly installed? Question open to everyone.