The Universal Mount w/Accessory Rail Mount is a self-locking mount with an adjustable mount design to easily mount and lock to your long gun. The mount adjusts to fit shotguns, all rifles and most scopes. The clamp offers a 12.5 millimeter adjustment allowance. The barrel and flashlight portion of the clamp adjusts 20mm to 32.5mm. The side of the mount has an accessory rail mount to attach additional firearm accessories. The mount is water and impact-resistant with protective rubber inserts to protect your gun and accessories when mounting. No tools required.