C-custom slides that are thickened and reinforced along the slide travel rails and around the chamber and firing mechanism. It's kind of made the slide resemble that of the SIG-Sauer's M1911 line. Also had to bolt the forward portions of the frame, but it let me use the rails to hold the compensators in place. I use double-stack magazines with slam pats and for style, gold-plated the magazine release, hammer, safety switch and trigger.