All Red Head aluminum couplings are Hardcoat Anodized per MIL-A-8625 Type III, Class 1 . No dyes or coloring are used. Hardcoat is a hard, dense coating formed by converting the surface of the aluminum alloy into a hard aluminum oxide. This process provides the completed part with a hardened surface that resists corrosion, abrasion, and reduces electrolysis. It also prevents excessive wear on the threads. Complies with NFPA 1963, 4.12 Corrosion Resistance .
Expansion Rings included with each coupling. Made from seamless soft anneal red brass tubing, UNS 23000 for maximum expansion without danger of breaking. Chamfered edge prevents cutting of hose.