#4 x 7/8-14 (#10) Radius O-Ring Fitting Black

The #4 x 7/8-14 (#10) Radius O-Ring Fitting Black is a precision hydraulic and pneumatic adapter designed for high-pressure fluid transfer applications. This straight-port fitting connects a #4 AN (male) inlet to a #10 AN (male) outlet, making it essential for custom fuel systems, brake lines, and air suspension setups where reliable, leak-free connections are non-negotiable. Whether you're building a high-performance engine bay or servicing industrial equipment, this adapter bridges different port sizes while maintaining system integrity under demanding conditions.

Manufactured by FRAGOLA using aluminum construction with black anodized finish, this fitting delivers corrosion resistance and durability in harsh environments. The radius O-ring design creates a metal-to-metal seal that prevents galling and ensures repeatable, secure connections without thread damage—critical when disassembly and service are required. The straight-port configuration minimizes turbulence and pressure drop, supporting optimal flow efficiency in fuel injection, nitrous oxide systems, and pressurized coolant loops. The compact footprint (3 x 1.7 x 3.5 inches) allows installation in tight engine compartments where space is limited.

Professional technicians, hot rod builders, and motorsports enthusiasts rely on FRAGOLA fittings for consistent performance across fuel systems, coolant circuits, and brake applications. The radius O-ring interface is compatible with standard AN port configurations, ensuring straightforward integration into existing plumbing without adapters or workarounds. At just 0.05 lbs, this fitting adds minimal weight while providing the pressure-rated reliability needed for both street and competition vehicles. Installation is straightforward: simply thread into ports hand-tight, then tighten with appropriate wrenches to specification—no special tools required.