We Stock a full range of aluminum adapters, including these Male Flare to O-Ring Boss Male. These are commonly used for fuel pumps, oil pumps, water pumps etc. The O-Ring Boss (ORB) is a UNF Thread with a O-ring recess cut into it for sealing and a radius for high flow . It is now very common to find oil pumps and fuel pumps and filters to be machined this way for a much more secure seal. We have a great selection at competitive prices. The O-ring is included.