#4 Male AN Union

The #4 Male AN Union is a straight adapter fitting designed to connect two #4 AN male ports in high-pressure fluid systems. Constructed from aluminum with black anodized finish, this coupling maintains structural integrity while providing corrosion resistance in demanding environments. The straight-through design eliminates flow restrictions, making it essential for hydraulic brake lines, fuel systems, and pneumatic applications where pressure continuity is non-negotiable.

AN (Army-Navy) standardized fittings are precision-engineered to military specifications, ensuring consistent thread pitch and flow ratings across manufacturers. The #4 designation indicates a 1/4-inch nominal bore—a common sizing for moderate-flow applications in off-road vehicles, motorsports platforms, and tactical equipment systems. Aluminum construction with anodized finish offers weight savings critical in racing and aerospace contexts while delivering chemical and oxidation resistance superior to bare aluminum. The black anodized layer adds visual definition on high-visibility assemblies and provides additional hardness against abrasion.

This adapter is ideal for technicians, motorsport builders, and system integrators who need reliable AN coupling solutions without the weight or corrosion concerns of steel alternatives. Use cases include custom brake line routing, fuel delivery system repairs, pneumatic tool connections, and prototype hydraulic systems where male-to-male coupling is required. The compact 1.9 x 0.6 x 2.8-inch dimensions and minimal 0.02-lb weight make it practical for space-constrained installations where every component's footprint matters.