One thing, especially if you get male rats, is the urine issue. The rats will urinate against the bars of the cage and it basically will spray out against the wall or anything else near the cage. Make sure anything around the cage can easily be wiped off. The urine can also make the cage itself a mess as it evaporates and leaves behind a sticky residue. This can be easily cleaned with warm water or a vinegar mix, but if you buy a cage that can open enough to fully clean, it will make it much easier. I just bought the Ferret Nation cage for my guys.