3/8 BSP Male x 3/8 Compression (NPT) Male
So are you having trouble finding a fitting to connect your European espresso machine to American plumbing? This is THE part you will need to install espresso machines in America.
More than likely because male threads for water inlet on 99% of commercial European espresso machines are 3/8" BSPP. (3/8 BSPP will measures 5/8 " ~ 16.5 mm NOT the same as NPT.) Need more info in understanding BSPP? The nerds over at wiki do a good job: http://en.wikipedia.org/wiki/British_Standard_Pipe.
Espresso Parts made this part so you can connect BSPP hoses to US Compression line. It is made from 303 stainless steel.
This fitting is a universal piece for sealing you may need either a copper or PTFE Gasket.