ProMag Industries SPR-A23B is a high-capacity magazine engineered for optimal performance and reliability. This 40-round extended magazine ensures your firearm is always ready, providing both durability and efficiency. Manufactured with a blend of traditional and modern techniques, this magazine features heat-treated high carbon steel for strength and mil-spec polymer for resilience. Proudly made in the USA and backed by a lifetime guarantee against manufacturer defects. 40-round Extended Magazine Constructed of a Proprietary DuPont Zytel Based Polymer Injection Molded Magazine Follower Magazine Spring Formed from Heat Treated Chrome Silicon Wire Upgrade your shooting experience with the reliability of ProMag products.