Hardline Fitting and Standard Parts:Only compatible with hard tube. 6AN to 5/16 inch,the thread size of the 6AN is 9/16UNF.It's fits to 5/16" OD hardline,please measure before perchase Aircraft Grade Material:6 AN male flare thread (9/16-18) to 5/16 inch tube hose fitting connector with brass insert Lightweight 6061-T6 cnc machined billet aluminum black anodized Black anodized finish Tightness and Corrosion Resistance:Manufactured to exacting standards for tight, leak-free connections. Connect 5/16" tube to -6 AN Male ends.Black anodized finish assure positive sealing and come in a corrosion-resistant finish Wide Range Of Applications:This 5/16 hardline to 6an fitting is widely used in Brake System / Air & Fuel Delivery/ Engine Modification / Oiling System / Cooling System Working Pressure and Temperature:Maximum working pressure: 4000PSI,Working temperature: -65°F to 252°F, Weight: 0.0881849048 pounds, Manufacturer: CNRAQR