SGM Tactical SSGMP30825: These magazines from SGM are made from a glass-filled polymer specifically chosen to provide an extremely durable and internally slick magazine that ensures smooth operation and durability that will serve for years of use. The springs on these mags are also slightly longer and are coated to provide uniform pressure and resist corrosion. These .308 mags were designed using CAD software to ensure a perfect fit for your firearm, and are manufactured right here in the U.S.A.