This Burris SpeedBead Beretta Rem 870 (300245) sight is an essential SpeedBead System. It is able to handle many factors that make wing shooters miss, and turns poor shooters into good shooters and good shooters into great ones. 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.