Wilson engineers took their world famous 47-series magazine-the choice of Military and Special Operations forces worldwide, and paired it with the longest, toughest spring we could find to create the ideal standard capacity 1911 magazine for serious shooters. The enhanced spring is perfect for high-round count training or those who have selected +P ammunition for their sidearm.This heavy duty spring easily compensates for the extra slide velocity caused by heavy .45 ACP loadings and resists reliability-robbing fatigue over time. Superior Wilson Combat-hardened stainless steel tube geometry in concert with our time-tested, no-tilt Convex nylon follower will improve feeding with almost any bullet profile and ensure last round lock back and enhance last round ejection even after thousands of rounds. The lo-profile steel baseplate easily withstands the rigors of hard, operational or training use.