Models Piano 26 and 27
are the first price melodicas
(the difference is they have different ranges).

Casotto 26 and 27
are up-to-date versions of the former.
They have a very special sound,
very soft, perhaps like an oboe.
The keys are a little bit hard to play
and the mouthpiece is too narrow
(but it can be played without it).

Piano 32 and 36
are the biggest models.
The 32 extends Piano 26.
As for the 36, it's a real rolls :
the bottom of the instrument is made of metal,
thus providing a bright and powelful tone.
The touch is very light so it's easier to be a virtuoso !
It can be played whith a strait mouthpiece
(like a trumpet mouthpiece)
or bended one (to see his fingers).

The melodicas with piano keys can be
played with a floppy pipe.
The advantage is that you could layer
the instrument on a table (and then playing seeing his
fingers or even with the 2 hands).
To my mind, that's not an interesting
use of the melodica.