The Daniel Defense Lower Parts Kit, Semi-Auto is for those interested in assembling their own AR15. Although there are many manufacturers of so-called MIL-SPEC parts, we have gone to great lengths to ensure the parts we provide are of the highest quality and compatible with a wide assortment of available receivers. However as we have developed this kit we have seen a wide variety of lower receivers; some from “manufacturers” of questionable quality. Consequently some of the parts may not fit properly in some of these receivers.