Short Cat column:  Have gotten these before from a different source.  Cost about the same but I prefer these (I got 2 short and one taller) and each "floor" is complete. In the ones I'd ordered from another source one floor was half.  these are particularly great for kittens.  I am partnered in a feral cat rescue and when we get a new litter of kittens these are the ones I use and they love them.  I would recommend.