I have a very large cat and most kitty beds are too small for him and he is falling out the sides.  He also loves the cave beds but hes too big for those too.  This one is bigger and both cats could fit in there snuggly. The back parts are high so he feels like hes in a tiny cave.  As soon as I put it down he ran into it and snuggled right up.  He didnt even get nervous when people were walking around because he feels secure with the tall sides.