The 17 Design & Manufacturing AR15 Stripped Lower Receiver is the perfect base for your AR15 build. Machined to mil-spec dimensions, their lowers work with standard AR15 components and ensure the highest quality and parts interchangeability. Additional features: Upper tensioning screw- allows user to fine tune the fit of the upper and lower through the use of a nylon tipped tensioning set screw in the grip tang of the receiver. Flared magwell angle- Wider angles in the magwell allow a more flared feel without increasing the width/footprint of the lower receiver. Features a threaded bolt catch pin. Mfg: 17 Design And Manufacturing