This is my second micro build. This is the Sirians 3 inch frame. Basically, it's a clone of the Micro Alien. The arms are not replaceable though, just a solid bottom plate. I was pretty impressed with the quality of the CF on this frame...clean cut, very stiff. The frame comes with carbon fiber tube standoffs, but one of the standoffs was not fully drilled and tapped so I ended up replacing them with aluminum ones.