The Whirl-a-wheel is a reasonable exercise equipment for my hamsters. It is easily attached to any tube or home and is completely enclosed with several small breathing holes. The axle comes together with a plastic screw and needs to be taken apart for any thorough washing. My two hamsters sometimes like to crowd into the wheel together and run in the same direction (however, watch out, if one of the hamster lags behind and the front hamster is still running, then someone is going to go head over claws and tumble in the wheel - very humorous, but nevertheless a dangerous arena for the young and uninclined hamster).
To conclude, I must mention that the Whirl-a-Wheel is not that squeaky - noise is usually generated because of leftover food, shavings or droppings found trapped in the wheel. That is another hindrance to an otherwise good product.
Hamster satisfaction: 
Maintainability: 
Owner satisfaction:
