The FN 509 Midsize MRD features a four-inch barrel and slide with optics mounting package, a midsized frame, standard 15-round capacity and is compatible with larger capacity FN 509 magazines with use of a sleeve. The improved controls aid in manipulation, the new improved texturing on the two included backstraps provides better recoil management, and a flatter faced trigger allows for more controllable trigger press and cleaner break.