The Hornady Security® Square‑Lok™ AR Upper Receiver Mount provides a simple, secure way to organize and store spare AR upper receivers on a Square‑Lok™ panel. Its all‑steel construction attaches at the upper receiver’s rear takedown pin lug, creating a solid mounting point that drops securely into the Square‑Lok™ system. Sold in a convenient three‑pack, it helps keep spare uppers organized, protected and readily accessible.