First I ordered a C15 unit, which was almost DOA, it rattled and gave a very bad noise, after a little time it stopped with F2 error.
After extended negotiation with the responsive product support I got FULL refund. After that I ordered the C20 unit which only differs from the C15 only in the lid design (and thus capacity). (the two lids as INTERCHANGEABLE).
The second unit works very good, little (35-53W) power consumption on 12V, good cooling performance, quite silent.
I'm quite satisfied.