Springfield Armory Echelon 4.0FC 9mm Luger 4in Black Pistol - 20+1 Rounds - Engineered to merge full-size capacity with a compact slide assembly, the Echelon 4.0FC pairs a 4-inch barrel with a full-length grip. At its core is Springfield's Central Operating Group, providing a serialized foundation for modular performance. The revolutionary Variable Interface System enables direct-mount compatibility with a wide range of today's leading optics. Fully ambidextrous and equipped with tritium/luminescent U-Dot sights, the 4.0FC delivers duty-grade capacity with fast handling in a balanced, do-it-all platform. Features Made in the USA ; Variable Interface System: By utilizing a set of movable pins, the Variable Interface System achieves a low, direct mount optics solution for improved sight picture and intuitive alignment; Central Operating Group: The Central Operating Group is self-contained and serialized, providing a robust housing for the patent-pending operating system;