I;ve got a small and medium phunnel and they both fit on my small egyptian. If you have a hose or a bowl that is too big to fit, just get a piece of wet paper towl and wrap it around the stem. then just put your bowl over it and it should have a snug fit
Good thing about it is that it will stop some of the juices from going down your stem since the towel will soak it up. Do the same around the ending tip of the hose into the hose port.
Sorry if this sound a lil confusing. If you wanna get a clear idea of what I'm talking about, just watch my "how to" setup a hookah vid
Its sorta in there when I list a "tip" when I'm showing how to put on the bowl:
I have a standard Egyptian bowl from H-S that is too big for the stem. I do the paper towel method and it works like a charm
My razan isn't airtight too so I did the paper towel thing and it helps a lot