Preferably nuts and olives.

Hi Don...

No olives here, but plenty of nuts! :) Will peanut butter and jelly work for you?


Mark

Preferably nuts and olives. I don't know about the olive but you got to nut here. Whadda want? Oh yea! Ya want to couple a 1/2 " pipe to a 15mm or another 1/2" (15mm=0.59 in.) pipe? Simple! Us a coupling.
You gave us no details, material of the pipes, a reason to convert to mm and left us with a silly question. Ya got our best shot!