Warning: This is an advanced treadmill and not for the intimidated or young hamsters. My hamsters were initially too young and hence their bodyweight was not enough to start the Sky Spinner turning. My hamsters were also distracted by the two end tunnels and instead of running (like on the normal Whirl-a-Wheel), I will find my hamsters entering the end tunnel and upsetting the momentum of the Spinner.
I tried placing the Spinner horizontally to provide my hamsters some living space. I did this by sealing the entrance of the spinner and connecting the two tunnels to the rest of the hamster city. A good alternative idea, however, the food (and other stuff) kept falling out of the spinner making the floor a great big mess. Well, in the end my hamsters decided to use it as their loo. I must say that the Sky Spinner is quite troublesome to wash and clean (you have to remove the screw and axle followed by the two end-tube closure disks and couplers).
Hamster satisfaction: 
Maintainability:
Owner satisfaction: 
