BSA Red Dot sight is lightweight and perfect for all types of shooting. Works on handguns, shotguns and bows. Turn on and a 4 MOA red dot appears in the center of the sight; adjust the brightness to fit your needs. Shadow black finish reduces glare; 11-position click rheostat. 3.8" scope length. Mounts on Weaver-style rails, includes lithium button battery and a limited lifetime warranty. Please note the red dot sights work by reflecting light from a light emitting diode off a mirror and back to your eye, in order for this to work, the unit must be slightly angled for the light to reflect off the mirror. Therefore, the mirror located in the ocular lense is tilted to allow for the reflection.