Made out of rubber which makes it durable.it can inflated and deflated n number of times. No cords, no batteries-just fun, healthy playtime. Riding hopper balls can keep kids active and maintain exercise, help kids develop balance and eye-coordination. This is one of the best toys for children's exercise and because kids can hop either inside or outside this is a must-have toy for any child. Jumping Hopper Ball can not only develop kids ability of balance and also keep kids busy, and get the energy out. It is an active and fun indoor and outdoor game for your kid. you can deflate it when not in use. bouncy balls for adults Rubber Hop Ball for Kids Made of thick and strong rubber, the hopper ball is durable and explosion proof. It makes kids’ reliable partner to help them strengthen muscles, learn how to maintain balance, and promote brain development. Hopper balls improve coordination, balance, and exercise. This is one of the best toys for children's exercise and because kids can hop either inside or outside this is a must-have toy for any child.