Daniel Defense took their battle-tested M4A1 design and made it even more operator friendly by adding a fully ambidextrous lower to provide right- and left-handed shooters with more flexibility and control. They also swapped out the RIS II rail system with their RIS III system, which reduces weight by using M-LOK attachment instead of picatinny. FEATURES: 14.5" chrome-lined, heavy-phosphate-coated Government profile barrel features a pinned & welded DD Flash suppressor to extend length to NFA-required 16" Fully ambidextrous lower enables shooter to operate important rifle mechanisms without moving dominant hand from rifle grip 12.5" RIS III Rail& Mfg: Daniel Defense