3/8 BSP Female x 3/8 Compression 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.) If you need more info on understanding BSPP the nerds over at wiki do a good job: http://en.wikipedia.org/wiki/British_Standard_Pipe.
The male threads coming out of your wall are more than likely 3/8" compression. You can purchase a long enough 3/8" x 3/8" compression hose to go from your wall to this fitting, which would thread onto the male water inlet connection on your machines pump.
This fitting is a universal piece, however for sealing you may select either a copper or PTFE gasket the be installed between this fitting and the male pump fitting.