Specification; Type: Fuel Rail Fitting Adapters Fitting Type: Fuel Injection Material: Aluminum alloy Size:6AN Male Flare To 5/16" Connection Type: Screw-On Application: fits stock return lines and supply lines of fuel filter and fuel rails Surface Finish: Anodized Package Including: 2Pcs Fuel Rail Fitting Adapter Note: Professional Installation is Highly Recommended Installation Instruction is NOT Included .