The New Frontier Armory C9 Complete Lower Receiver is the perfect start for your next pistol-caliber carbine build! Designed from the start to accept the battle proven double stack Glock magazines in 9mm, .40 S&W, .357 SIG, and more giving you true multi-caliber flexibility in your build! Fully compatible with most standard and aftermarket AR-15 parts, this lower features a proprietary magazine catch assembly and ejector factory installed, in addition to the ergonomic and proven Shockwave Blade Pistol Stabilizer!