I think the post while very fun is way off the mark.  Too easy to tear sides, bounces when a cat climbs on it and rocks.  It just is not stable.  I hold my breath everytime my small girl sleeps in the little round bed!!!!  The sisal is very short - should go all the way up and the legs are sooooo narrow I think that is why it is tippy.  My cats are fairly young.  Old or sedentary cats is what you should have advertised it for.  I have a small kitten and she even makes it wobble.