Have a Ball. Add a little bouncin' ball fun to your next party or event with a knobby bounce ball. With so many varieties, we are sure to have the one your guests will love! One knobby ball. 7" long and wide inflated. Ball sold deflated. Assorted colors. A bounce ball makes a great party favor, giveaway. Also a great addition to your party gift bags. A classic toy that entertains all audiences!