9mm Luger caliber; 4-inch Hammer Forged Steel barrel, Melonite finish, 1:10; Compact Dimensions - Shortened at the frame and muzzle, the Echelon 4.0C boasts full-size features in a concealable package; The Central Operating Group is self-contained and serialized, providing a robust housing for the patent pending operating system; OD Green Cerakote - Finished in Cerakote to exceed the most rigorous demands, ensuring your firearm stands strong when it matters most; A shorter 4-inch barrel and compact frame for enhanced concealability; The serialized Central Operating Group is housed in a compact frame, offering a 10-round capacity with the flush magazine; Its revolutionary Variable Interface System provides unmatched direct-mount compatibility with today's leading red dot sights; Tritium / Luminescent Front, Tactical Rack U-Dot rear sights; A double-zipper case is included with each Springfield Armory handgun