Bg 2 piece mount system for 1" a-bolt shotguns FEATURES-Two-piece-Matte black-Standard height (for scopes up to a 44mm objective with a standard barrel contour)-Machined from 7000 Series aluminum for high strength & durability-The integrated design eliminates alignment problems and the possibility of a loose connectionbetween bases and rings-These fit theoriginal A-Bolts or A-Bolt II receivers only. They do NOT fit the AB3.