The hopping rabbit was made by his great grandpa but it never worked well due to the wooden wheels slipping on the floor. When his mother was his age, grandpa (aka: I) added the black plastic items on the wheels (extra credit to anyone who can ID them)which allowed enough 'tooth' to make the rabbit hop on carpet. Now that most of the house has wood floors, we added rubber bands which make it work well on slick floors. It took fifty years and four generations but we finally got a nice hoppy rabbit toy.