think of it as legos for big boys
it includes everything but the lower receiver(which you have to buy from a FFL). now please doont confuse a build kit with a LPK which is nothing but the little parts that make up the lower half(included in a complete kit). at this point though DPMS and Smith & Wesson both have budget ARs that are almost as cheap as a build kit so it's not really worth it anymore. 5 years ago build kits could save you bookoo bucks...not necessarily the case anymore but palmetto states kits are decent priced and are more highly recommended by many than mid range brands like stag and bushmaster.