Advanced Technology AR-15 Rifle Length Free Float Forend Combo Rail Package with Two 12in. & Six 4in. Aluminum Picatinny Rails has been discontinued by Advanced Technology and is no longer available. Our product experts have helped us select these available replacements below. You can also explore other items in the Tactical Rails, AR15 Tactical Rails, Riflescope Mounts, Rings & Bases, Gun Parts categories yourself to try and find the perfect replacement for you!