This factory FN magazine sleeve is made for running full-size 17-round 9mm magazines in the compact-framed FN 509 Midsize. It fills the gap between the base of the grip and the magazine floorplate, giving your support hand a continuous surface to index against instead of a step, which noticeably steadies recoil control during fast strings.

Because it is an FN part, fit is exact and there is no rattle or slop that aftermarket adapters sometimes introduce. A worthwhile addition for anyone carrying a midsize 509 with full-size spare magazines, or running the pistol in competition and practice.

In stock and ready to ship straight to your door from Dawson Defense, an Arizona-owned licensed dealer.