re
if they are the kind where the slots don't
go all the way through, so the inside/bearing surface is smooth. Mine
are this type, smooth on the inside.

you're right ...good screw type hose clamps are smooth on the inside..
with one other feature ..
the edges are curled up a little so they don't dig into the hose they are
clamping onto.

I don't know the brand...
the ones I get and use are like VW original euqipment hose clamps ..
they kind they used before they started putting on those spring things on
during production..
which looks to me to be around 84 or so , depending on which model vanagon.
Before then they used screw clamps on coolant hoses etc.

these clamps have a 6 mm hex head  ( using a screw driver to tighten them is
not good enough really ...
use a 6 point 6mm socket on a quarter inch drive rathct - that works well.

the 'feul hose' size I get ....
little spendy - might be 80 cents per ...
but they work very well.

all screw type clamps should be checked for tightness once in a while.
Don't keep creaming down on them of course ...
jsut snug them up a little once in a great while.

I don't trust spring type clamps, have seen them not squeaze tightly enough
sometimes...
and they are a hazzard ....like they can fly like bullets working with them
sometimes.

scott