Trusted by experienced shooters across the country, the Atlas Gunworks® Overpowered Magazine Spring +18% is a drop-in spring upgrade, built to ensure smooth operation and consistent feeding performance in any competitive or personal defense application. Durable stainless steel construction offers exceptional strength and lasting service life. Plus, this high-strength magazine spring is designed to be used with the Atlas Lockback Follower (not included) but will work with most factory OEM followers.