We're always asked about how we'd build a gun right out of the box. Well, this is it. These parts would go on our first gun, out of the box, no questions asked. However, where you see two similar items (with the stocks), it means if we were going collapsible, we'd go collapsible, and if not, the Mesa is what we'd be using, or the field stock. Of course, if you have the black gun, choose the black parts, and if you have the Titanium Cerakote gun, choose the NP3 parts.