ATI's OMNI HYBRID MAXX features a fully-patented metal reinforced polymer upper receiver along with a fully-patented metal reinforced polymer lower receiver.  The Omni Hybrid lower features a patented hammer and trigger pin retainment system, preventing movement from the hammer and trigger pin during firing.  The Omni Hybrid also features their patented over-molded metal insert, which reinforces the buffer tube housing and rear takedown pin.  This allows for metal-on-metal contact with both the buffer tube as well as the rear takedown pin thus increasing strength and durability from recoil and consistent firing.