Going Crazy, Running In Circles, Or Both

One of the kittens favorite "purchased toys" is the Crazy circle. I have had this toy since September and the kittens still play with it. I don't keep it out all the time but I do rotate it and it spends a couple day a week out. Both the kittens spend a good amount of time trying to "catch the prey". The toy is still in excellent shape and though they use it less than when brand new they still use is for a significant amount of time. I gave one to Lucy and Bailey my sisters two kittens at the same time with similar results.(8/9 Arwen typed this)
When I first got it Arwen was the only kitten I had and she used it non stop for at least an hour and a half.
Of course some of the favorite toys are the free things that are around the house(2q1 Smokey typed this) such as balled up paper, the tub, plastic caps from milk containers etc.