What makes SGM Mags uniquea |All of SGM's mags are engineered through CAD (Computer Aided Design) systems and manufactured to SAE standards in an ISO 9001:2000 approved manufacturing facility right here in the USA. SGM's injection molds are cut from P20 pre-hardened tooling steel and the retractable cores are cut from S-7 heat treated steel. This gives SGM absolute accuracy of all mag components for years to come. Longevity Gives Us Perpetual Performance.The Dupont composite/glass-filled polymer was specifically chosen to provide an extremely durable, internally slick, fast feeding mag that will provide years of service. SGM springs are slightly longer to provide a more uniform pressure and are specially coated to provide smoother action along with resisting moisture. All of SGM's mag designs are tested for perfect fit, smooth, fast, reliable feeding and durability. Continuous smooth feeding is mandatory; therefore, SGM tested their mags with a variety of ammo from various manu...