The AR-F3 (Flattop FastFire Mount) is designed to protect the newer FastFire III but will accommodate older FastFire I and II models. Easy to install on any AR platform, pistol, rifle, or shotgun, it's a great accessory for multi-gun shooters. Mounts low enough to use alone or as a co-witness for your iron sights. Provides easy access for illumination controls and also features a compartment for carrying a spare battery, open-end wrench and Torx wrench. Fits any Weaver or Picatinny-style base Mfg: Burris