Factory Browning A-Bolt Intermediate Height Two Piece Scope Base, Matte Black Integration offers strength and consistency. Browning's Integrated Scope Mount System unitizes the ring and base into a single, ultra-rigid unit. Machined from 7000 series aluminum alloy, they eliminate alignment problems and the possibility of a loose connection between the base and ring. They are available in .400" Standard height, .500" Intermediate height and .600" High height versions to fit your needs. This item is the intermediate size Integrated Scope Mounts unitize the ring and base into a single, ultra-rigid unit Machined 7000 series aluminum that eliminates alignment problems and the possibility of a loose connection between bases and rings Scope Ring System Height Selection Guide:p - Use the Standard (low) ring height for scopes up to a 44mm objective with a standard barrel contour. - Use the Intermediate (medium) ring height for scopes up to a 50 mm objective with a standard barrel contour. A-Bolt is referring to the original A-Bolt, the A-Bolt II and the A-Bolt Shotgun. Bases for these firearms are not compatible with AB3 or X-Bolt Bases.