This is a Aero Precision Stripped Lower Receiver known as the Stripped Lower chambered in 223 Remington, model APAR501101C.
The Aero Precision AR15 Gen 2 Stripped Lower Receiver is the perfect base for your custom AR15 build. Machined to mil-spec dimensions" these lowers work with standard AR15 components and ensure the highest quality with a correct component interface.
Features:
Works with standard AR15 components and magazines
Perfect base for your custom AR15 build
Machined to mil-spec dimensions