It is a non-metallic lower, but if it can live with the stress a 45acp puts on it, it will go forever with a 9mm. Eliminating a polymer lower really restricts your choices in a small pistol for anything being made currently. They are much lighter than even an aluminum frame and probably last longer than aluminum due to the steel inserts the slide runs on in most cases. I am a pretty hardcore single action trigger snob, but I can live with the triggers on the Shield and the Canik that I picked up. These safe action triggers have come a long way.
