FN 66100781 : Full-size punch in a compact package with FN\'s patented Low-Pro le Optics Mounting System and unparalleled modularity of the FN 509 platform, the FN 509 Compact Tactical. The pistol is 9mm and striker-red with 4.32\" barrel and the capability to accept all higher capacity FN 509 magazines. The patented FN Low-Pro le Optics Mounting System accepts nearly all commercial miniature red dot optics and features blackout iron sights that co-witness.