(S): Outside / long 31CM, wide 31CM, doorway high 18CM;
                           Inside / long 29CM, wide 29CM high 27CM, about 4 pounds for dogs and cats.
   (Medium): external / long 36CM, wide 36CM, doorway high 20CM,
                           Inside / long 33CM, wide 33CM high 30CM, about 6 pounds for dogs and cats.
   (Large): Outside / long 43CM, wide 43CM, doorway high 21CM,
                           Inside / long 40CM, wide 40CM high 38CM, suitable for cats and dogs 11 pounds or so.