Browning integrated scope mount system utilizes 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. Features: - machined from 7000 Series aluminum for high strength and durability - the integrated design eliminates alignment problems and the possibility of a loose connection between bases and rings -.400" standard height,.500" intermediate height,.600" high height. Specifications: - rind diameter: 30mm - mount pieces: two piece - ring height: high - material: alloy - screw quantity: 4 - bases screws: 0.25" - ring screws: 0.375" - weight: 3.2 oz - pockets: matte - color: black. Note: these fit the Ab3 only. They do not fit original a-bolts or A-Bolt II Receivers.