Specs Alpha Epsilon Systems AES-15 Billet Lower Receiver. Machined from a solid block of 7075-T651 aluminum on our multi-axis CNC mills to exacting tolerances that exceeds military specifications, the AES-15 lower receiver has a smooth flowing design, perfect for any high-speed, low-drag application from the competition field to the deer blind. Features include Integrated and enlarged trigger guard Flared magazine well Safe and semi pictograms engraved on the left side Thread