We go through a new hamster ball every 4 months or so as our hamster chews the inside clips off whenever she gets the chance. The savic one is much better quality and nicer for the hamster than the other brands (particularly our large local pet shop, part of a national chain, that sells only their own not very nice brand of hamster ball). The savic balls are clearer plastic, more lightweight, and have marginally smaller width air holes so their little paws can't get trapped accidentally. The medium size is perfect for a syrian hamster. It comes in a variety of colours , but so far we have had one yellow and one green from amazon, both were good colours and it is hard to find savic ball in petshops now so I am grateful to amazon for selling this particular brand, which far exceeds other brands in terms of hamster balls.