W&H assistina 301 plus Instructions For Use Manual page 16

Start-up
02697000
The built-in air filter in the connecting hose is only a fine filter.
It cannot clean unfiltered and possibly contaminated compressor air.
Dirty fine filters must be replaced.
> Use only non-contaminated,oil-free,dry and filtered compressed air according to ISO 7494-2.
16
Push the quick release coupling of
the connecting hose into the
coupling socket on the Assistina.
Connect the compressed air line.
General
Fit the suction filter so that it
is leak-tight.