18cm Hamster Exercise Ball Gerbils Ball Wheel Sturdy Stylish Toy for Small Animals Blue Description: [Hamster ball size] diameter approximately 18 cm/7 inches, perfect for hamster, mouse, and other small animals [PP Material] hamster exercise ball made of PP materials, environmentally friendly, transparent ball, convenient for owner, watch every pet movement [Good ventilation and breathability] hamster running wheel with multiple ventilation holes both more breathable and allows hamsters to exercise aerobically [Easy to install] Both hamster covers are designed with buckle lock, screw mount, can be molded with light press, convenient installation [Interactive Toys]Fun exercise toy to keep your hamster alert and agile, provides interactive play for your pet and owner Size Chart: Ball diameter: about 18 cm/7.09 inch The package includes: Optional