First thing that makes our patented gas piston system uniquely different is our one piece bolt carrier with buffer technology. To learn more CLICK HERE. Second, we designed a system that would be versatile with different calibers from the AR-15 to AR-10 and other variant rifles. Our unique design that has allowed us to get the 7.62x39 piston uppers running reliably has also allowed us to get the 7.62x39 piston mid lengths running reliably also...yes a 7.62x39 mid length piston upper! Our gas piston design that allows this versatility also allows us to run the 300BLK reliably with supersonic and subsonic without a silencer. It is what has allowed us to go from the AR-15 piston platform to the .308 and AR-10 piston platform with great success and reliability! Third, we use the highest quality of materials in our piston system.