Eaton Weatherhead C3269X10X8 Carbon Steel Fitting, Adapter, 1/2" NPT Female x 5/8" O-Ring Boss Male (Pack of 4) Adapts 1/2" NPT female end to 5/8" O-ring boss male end Carbon steel for durability and resistance to rupture under high pressure For use with LP and natural gas, refrigeration, and hydraulic applications