Some trapshooters use them. They are 2 extensions off the rib to be used as sights for the off eye. Their problem is that the angle of convergance (line of sight, off eye, and center line of barrel) comes to one point only. Shooting a game with similar distance shots, works best. Adding a second full rib works the same. Some shoot very well with this set up. The best set up for trapshooting is a mirror system where you see straight down the rib with the off eye. (Custom made)