It's a VOMZ Pilad PF 01x25 Russian dot. It mounts to vent rib. All aluminum. Uses a large fiber optic rod to gather and project light onto the glass optic. I'm actually very impressed with it. I did have to do some drilling of the vent rib to get the mounting brackets to fit. The spaces between the barrel and rib were very narrow/thin on this gun with it being a .410. The sight would have mounted flawlessly on a regular 12 or 20ga