Attaches to 30mm rifle scope tubes, allowing you to mount a backup sighting system atop your rifle scope 30mm ring fastens around 30mm scope tubes, installing via two set screws and included hex key The Picatinny rail mount will accept any standard Picatinny red dot/reflex sight or other optics Crafted from sturdy, lightweight aluminum, the rail mount weighs 2 ounces and is 2 inches in length