MBWorld.org Forums - SLK/R171 Fuel Hose Size?

Does anyone know the size of the rubber fuel injection hose used around the fuel pump and filter on a SLK320? American sizes go from 1/4" to 5/16" to 3/8" to 1/2". I wonder if there are corresponding metric sizes. I'm going to replace the fuel pump and filter soon and want to buy some fuel injection hose ahead of time. There are quite a few MB models that use the same fuel pump and filter, so the hose is in widespread use. Thanks.