[velma]

Size depends on your individual hamster. But the bigger the cage, the more cover you'd want in it. If you're looking to get a tank style cage so you have a lid, you'll probably be tempted to put a few taller toys in there so I'd say mesh it it or buy one of the duna multy tanks which have narrower bars. Hector busted for me the idea that robos can't grip or climb when I found him climbing onto his house and monkey baring round the roof of his tank...