I was starting to feel guilty because my chinchillas have a double FN, My ratties have a double FN, but my poor ferret Rowdy only had a one level cage (and run of the house heehee). Petsmart had the FN142 on sale for 219.00 and I got it this week! Now there is equality among my critters. At first Rowdy wasn't so sure of this giant monster with bars, but after a short time.....he loves it!!