Elevate your shooting experience with the ProMag Industries GLK-A20 High Capacity Magazine, crafted for durability and reliability. Constructed from a combination of heat-treated high carbon steel and advanced polymer technology, this magazine promises seamless performance and longevity. Drum housing constructed of a proprietary DuPont Zytel based polymer Magazine upper tower features a full length steel internal insert, stamped and welded like the factory magazine Injection molded magazine follower for smooth feeding Magazine spring formed from heat treated stainless steel for optimal durability Manufactured in the USA for superior quality Trust in a product backed by a lifetime guarantee against manufacturer's defects.