The Burris SpeedBead Sight For Beretta 3901 (300246) is a red dot reflex sight system, which provides the advantages of optics without the height, weight, or loss of balance normally associated with adding optics to shotguns.
Shooting instructors emphasize the importance of proper stock-to-shoulder fit and mounting the shotgun into exactly the same position every shot. Maintaining proper form on the trap range is one thing. Maintaining it in the real world of flushing pheasants, quail, grouse, and fast-flying waterfowl is another.
With the SpeedBead System, both the target and the red dot remain in focus. The optics and their position on the sight plane eliminate the need for perfect left/right, up/down head position for an accurate shot.
The innovative mount puts the center of the optic directly in line with the ventilated rib, so altering your shooting style is not necessary. And with 3-1/2 inches to 4-1/2 inches of eye relief, there is absolutely no worry about your eyebrow running into the sight nor any interference with your hand gripping the shotgun.
Should the common CR-2032 five year battery ever fail, you can revert to your front bead without visual obstruction.
For a better view on rising targets, there are 1/8" and 1/4" risers available.