BudsGunShop.com - Parts Made of ?....

most of the parts are metal Features and Specifications:
Manufacturer Number: G2-K421-A000-0P
Standard lower parts kit for AR-15 platform firearms
Stainless Steel hammer and trigger
Pistol grip and trigger assembly included
Finish: Black
Fits:
AR-15 lower receivers

Same deal Edgar. This is a metal "Mil-Spec kit Sir. google.com/search?q=661799410205&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiv6Nvh5JfjAhUDhOAKHUzAAYwQ_AUIEigD&biw=1280&bih=596#imgrc=3YfGYPCBbbCH1M:

Edgar, Almost all parts are metal. If your looking at this lower kit the roll pins are coiled they bend and twist and are not the quality of slotted roll pins. Beware.