Well, they have a solid running surface, there are no pinch areas, they are very quiet, come in a wide range of 2 tone colours, oh and there are holes in the side so that the hamster can get in and out of the wheel - In general I think hamsters seem to feel more secure in these wheels. - I have 3 of them and I would recomend them to anyone, but beware the senior sized wheel is very big - more suitable for a rat or a really big hamster. the next size down is more than adequate for most hamsters.