WHAT DOES FO FRONT MEAN?

† Notice: The receiver-mounted, Picatinny-fashion rail is made to accommodate most optics and optic mounts meant for use with Picatinny/ MIL-STD 1913 rails. Having said that, as a consequence of diminished clearance involving the very best in the receiver and The underside of your optics rail, optics and optic mounts that extend much more than .A