Central Operating Group (COG) is self-contained and serialized, providing a robust housing for the patent pending operating system; Tritium-powered U-Dot sight picture of the Echelon is intuitive, accurate, and fast; Variable Interface System (VIS) achieves a low, direct mount optics solution for improved sight picture and intuitive alignment; Deeply machined crisp serrations offer a strong grip in any condition; Creating a natural index point the Forward Trench assists shooters who charge or press check their firearm from the front of the slide while keeping hands clear of the action; Further enhancing the ability to manipulate the firearm the rear of the slide is flared for additional engagement; Features a capacity of 17+1 in its flush fit configuration and 20+1 with the extended base pad installed; Ambidextrous slide stop and magazine release for intuitive use; Alternative grip modules (small, medium, and large) give shooters the ability to find a configuration that fits them best. Each grip module accepts the Central Operating Group and all three backstraps; Double-zipper case included