Impact-resistant polymer construction Dependable fit and finish Enhanced ergonomics Tool-free installation Favored by CCW holders and home defense shooters across the country, the FNA(R) 509(TM) Midsize 9mm 17-Round Magazine Sleeve is a lightweight, yet durable polymer sleeve, designed to deliver improved comfort and control with 17-round FN 509 magazines. This magazine sleeve features impact-resistant polymer construction, integrating seamlessly with your pistol's frame for reliable, snag-free performance. Plus, this magazine sleeve is easy to install for frustration-free, field-ready service! Compatible with factory 17-round magazines only.