When the time comes and you have decided to build your own pistol caliber carbine based off of an AR style platform trust Spike's Tactical to deliver the receiver set you need to get the job done. This particular receiver set features a matched upper and lower built from the same material so you can be assured of a quality match up. The lower is designed to use Glock style magazines which makes it convenient with the massive amount of factory and aftermarket magazine choices. There are several pockets which have been machined to help reduce weight while keeping the set strong. All edges and surfaces have been 3D chamfered to reduce snagging. The receivers are made from 7075-T6 Aluminum and feature a hard coat anodized matte black finish.