These brilliantly glowing beads stand out in all light conditions. Bright enough to see clearly but unobtrusive enough to not alter the traditional look of your shotgun. Bead size is .070" (nominal). Notes: The Fiber Optic bead is bright enough to see clearly but unobtrusive enough to not alter the traditional look of your shotgun. A great companion with Marble's Fiber Optic Universal Rear Sight.