Put your small animal pet inside the wheel of the Critter Cruiser and watch the fun begin. Let him race around the house, or around the Run-About Hamtrac (sold separately). You can also set it so that the Cruiser remains stationary while he runs in the wheel, or you can take the wheel out of the Cruiser and use it by itself. Made of easy-to-clean, smooth plastic with rounded corners and no sharp edges. Wheel is well ventilated for your small pet's safety and comfort. Cruiser comes in assorted, bright colors. Please let us choose.