There is also a Guinea pig sized Ferplast Sin. Again way too small for a guinea pig but not a bad size for a hamster. It's smaller than the first guinea pig house though.
https://www.amazon.co.uk/Ferplast-Gu...inea+pig+house
It's a good size for a hamster though. I went with the bigger rabbit one because it was big enough to fit a litter tray inside after our hammy moved his toilet corner inside his house.