A couple years ago, finding an LPK (Lower Parts Kit) to complete an AR-15-pattern lower was significantly more difficult than it is today. Demand was quite high, and companies that normally supplied these kits found their supplies rapidly depleted. One good outcome of this shortage was numerous new companies stepped up to fill the demand.
CMMG was one of those companies, and I recently received the standard AR-15 Lower Parts Kit the company offers. One thing that helps the CMMG LPK stand out is the use of different colored bags for different parts broken out more or less by function. The blue bag has magazine- and trigger guard-related parts; the green bag has the safety-selector parts and the pistol-grip screw; the red bag has the trigger- and hammer-associated parts; the yellow bag has the bolt-catch parts and buffer-retaining pieces and the clear bag has the takedown pins and springs. The pistol grip, hammer and trigger assembly are separate.
It's a simple, yet ingenious way to keep things straight for even the greenest of AR-platform owners. As an additional bonus, CMMG has a handy video with instructions on where and how everything goes together. If you've been thinking about finishing your own AR-15 lower, there's everything you need here to do so.