To a cat, boxes are Personal Kingdoms.
A box is a secure, enclosed environment that triggers a cat's natural instinct to find a safe den. Curling up in a box lets a cat keep watch while feeling hidden & safe. Boxes help to keep things toasty for our feline friends. The cardboard acts like a cozy blanket, trapping the cat's body heat and acting as an insulator. The tighter the fit, the better.
This box is a challenge - but it's still a keeper.