The TandemKross Green Spring Magazine Spring are perfect for upgrading your Ruger MK series magazines with aftermarket magazine springs. Magazine springs wear and tear over time, reducing the performance of your magazines and resulting in failure-to-feed issues. Don't let an under-performing or missing spring derail a shooting sports competition or day at the range! The new "Green Springs" for Ruger MK Series are shot-peened for a significantly longer life than the factory spring. The upgraded magazine springs reduce failure-to-feed issues and are an ideal replacement for your old, broken magazine springs. "Green Springs" are an ideal upgrade to keep in your range bag for easy maintenance on the go. The dark green color of the magazine springs is a simple way to show your #TANDEMIZED pride and keep your upgraded springs separate from factory springs.