Powerflow manufacturers a full range of aluminium adapters, including this 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. 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.