Marble’s® Extra-Lum "Expert" shotgun beads have 500 percent more light gathering qualities of our standard florescent beads. This extra bright bead really stands out in any light conditions. You can really rely on the brilliant Extra-Lum "Expert" bead. The UV protected fiber optic cable is permanently bonded to our machined from solid steel base. The ends are highly polished to further guarantee as much light transfer to the eye as possible. Waterfowl hunters and clay target shooters will find the Extra-Lum "Expert" a true enhancement to their shooting abilities. >>"Expert" Sight Specifications