That box is designed for pigs stunning by means of C02.
Four animals of max. liveweight 150 kg each, are lowered at the same time.
When the lift reaches the bottom, the animals are stunned with C02.
After approx. 30 sec. the lift goes up and well stunned pigs are ejected on the table for sticking.
That way of stunning is the less stressful for the animals and completely eliminates their suffering so the meat quality is the best.