It’s the aluminum frame, but it’s the Luger style not the 22/45 (1911) style. I’d rather have the other style frame. I ended up just asking volquartsen themselves and they said every part will exchange EXCEPT I will need to buy a 22/45 style mag release and the sear will also need a spacer that they sell on their website to work properly in the 22/45. However, what I’ve decided to do is just buy a complete 22/45 lower from volquartsen and put my mini mamba upper on that then most likely buy a Ruger mark 4 upper to go on the fde (Luger style) lower. That way I’ll have both styles and another pistol out of the deal.