90011 Size: 4.5 Features: -Wheel. -Available in several sizes. -Wire mesh exercise wheel perfect for mice and small pets 4.5". -6" wire mesh hamster/gerbil exercise wheel. -8" hamster/gerbil wheel with mesh for easy safe footing for pet. -11" wire mesh ferret wheel with mesh for easy safe footing as animals runs. Specifications: -4.5" Dimensions: 4.5" H x 3.5" W x 4.5" D. -6" Dimensions: 6" H x 4" W x 7" D. -8" Dimensions: 8" H x 4.5" W x 8.5" D. -11" Dimensions: 11" H x 5" W x 10" D.