Made with pet safe materials.Upgrade quality ABS material, so it can be long lasting and not easy to broken.Relieves boredom and increases activity level and giving him a fun spot to play .4.7-inch diameter. Ideal for dwarf hamster .Encourage healthy exercise in a secure and safe way .Makes a great temporary holding area to keep your furry friend while you clean their home .How To Assemble the Hamster Plastic Ball : 1.Align the buckle positions of the two hemispheres, buckle up to the correct position, and turn slightly clockwise to lock 2.When covering the top cover, pay attention to align the four snap positions , and turn to the right to fix 3.Put your hamster into the plastic ball and watch them play on the flat floor .Fun exercise toy to maintain your pet's alertness and agility.Provides interactive fun for the pet and the pet owner .