Light and tough, the FastFire series puts an unmistakable, bright red dot on your target to give you an immediate speed and accuracy advantage. Can be used as a primary sight or paired on top of an existing sight. The FastFire 3 provides 3 manual brightness settings, plus an automatic brightness adjustment setting. The top-mounted battery offers easy access, without removing the sight. Windage and elevation adjustments are accurate and easy to use. TECH NOTE: The FastFire 3 will easily work with the Glock MOS system. Bright red dot allows for fast target acquisition and easy aiming Compact and lightweight, so it won?t affect firearm balance or handling 1x magnification allows both-eyes-open shooting, for enhanced awareness and target acquisition Parallax-free, for better accuracy Mounts to almost anything?including handguns, rifles, and shotguns?using Burris mounting systems Automatic brightness sensor adjusts brightness to match the environmental conditions; also features 3 manual brightness settings Windage and elevation adjustments make optic fine-tuning easy; no special tool required High-grade optical glass provides excellent brightness and clarity, with lasting durability Index-matched, Hi-Lume multicoating provides low-light performance and glare elimination Waterproof Shockproof design stands up to years of punishing recoil CR1632 battery included Battery access is conveniently located on the top of the sight Comes with our Burris Forever Warranty REFURBISHED products may or may not include accessories.