Are these fridges compressor-based like the larger fridges or Peltier (thermoelectric) like a lot of food "hot/cold boxes"? The latter are hugely inefficient, t

Are these fridges compressor-based like the larger fridges or Peltier (thermoelectric) like a lot of food "hot/cold boxes"? The latter are hugely inefficient, though on such a small scale maybe it doesn't matter as much...