This is a Glock 17 Gen4. I milled a window in the top of the slide and then cut 3 ports in the barrel centered in the window. I then attempted to match the Anodized aluminum pieces on the pistol. The owner didn't like the color so we decided to do a 2 color Cerakote with some tattered stars and stripes. The Cerakote on the is Sniper Grey and Graphite black.