Aeromotive 15101 Ford OE return line, 3/8" Female Spring-Lock to -6 AN male Constructed of 6061 T6 aircraft grade aluminum or stainless steel, each component is CNC-machined for precision fit and unmatched flow All billet aluminum fittings are anodized Type II bright dip black for corrosion protection and unrivaled aesthetics We offer a complete line of hard to find fittings from OEM specific connections to AN adapters All Aeromotive fittings and adapters are fully compatible with gasoline and alcohol based fuels Thread Diameter: AN-06