I hurriedly ordered this for my daughter's pet rat, Lumpy, who seemed to be languishing away in his 20 gallon aquarium "home". I couldn't stand to see him with no room, no toys, and very little interaction.
once the unit arrived, and it was 3/4 assembled, I realized it was not actually built for a rat. even though the advertisement stated it could be used for a rat.
The bars of the horizontal "floors" were spaced too far apart for a rat to comfortably navigate easily, so I had to do some customization of the cage to get it to work.
First, I removed the bottom sliding floor that was suspended above the cleaning tray. The cleaning tray, filled with paper "bedding" was already familiar to Lumpy, so it is more comfortable to him right off.
I then covered the middle "floor" with corrugated plastic sheet from Lowes. I measured and cut the openings as needed, taped the edges, and laid them in place. it worked great!
I also zip-tied all of the cloth covered half "floors" and ramps in place as they seemed to be dislodged rather easily by Lumpy's wanderings in his new home.
The difficult part was, with the sliding floor gone, there were openings in the front %26 back of the cage, that were normally filled with the sliding floor. I measured, cut, and duct taped some horizontal panels in place, to keep Lumpy from escaping.
I then placed his new home on the floor, between the (2) living room windows. Half of the cage is in shade, and the other half is bathed in sunlight. So he can choose his preferred location.
He has been in his new home almost 2 weeks, and is happier, and looks much healthier. The next step is to get a wheel for him to run on.
Bottom line: This is a beautiful piece of furniture that is built probably for a Chinchilla, Hedge hog, or something of that size. It is not size appropriate for a rat or mouse. But it works (after modifications) for my situation.