Aeromotive 15644 AN-06 Bulkhead Fitting All Aeromotive fittings and adapters are fully compatible with gasoline and alcohol based fuels. All billet aluminum fittings are anodized Type II bright dip black for corrosion protection and unrivaled aesthetics Constructed of 6061 T6 aircraft grade aluminum or stainless steel, each component is CNC-machined for precision fit and unmatched flow More area and smoother transitions from the inlet to the outlet, resulting in less restriction than any other fitting line Thread Diameter: AN-06