Features: Black anodized aluminum ensures corrosion resistance and leak proof sealing for fuel, coolant, and air systems. Precise machined hexagonal head design ensures easy wrench installation and vibration resistance in harsh engine environment. Designed for automotive enthusiasts, professional mechanic, and DIYers upgrading turbocharged engines or high performances fuel systems requiring ethanol fittings. Optimizes fuel line connections during engine maintenance, or fluid system repairs where dust prevention and reusable adapters are essential. For universal AN4-AN12 compatibility, featuring double seal technology that outperforms standard steel fittings in vibration resistance. Specifications: Component:aluminium Product size: AN4(16x14.9MM); AN6(18x14.9MM); 8AN(22x17.8MM); AN10(25x19.5MM); AN12(30x23MM); Package Includes: 2pcs Fuel Line Adapters note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you donot mind befores you order. 2.Due to the differences between different monitors, the picture may not reflect the actual color. Thanks for your understandings.