This Adams Arms AA-15 is piston-driven and features a mid-length system, a 1/7 twist, a Magpul MOE-K+ grip, MOE SL adjustable stock, M-Lok rail covers, and a muzzle brake. Two 30-round magazines are included. Get the best bang for your buck when you get a Certified Used Firearm. When you see the Certified Used stamp on any of our firearms, you can be confident that you're getting exactly what you want - a gun only in very good to excellent condition and held to the highest quality standard. All Certified Used Guns come with a 'no questions asked' return policy.