made from top quality synthetic rubber for maximum springiness , size : 22, 27, 30, 32, 35, 38, 42, 45, 49, 55, 60mm.With CE. The high bouncing balls (Bouncy balls ) are made from top quality synthetic rubber for maximum springiness. Sizes (diameter) from 22 mm to 60 mm. Detailed sizes are 22, 27, 30, 32, 35, 38, 42, 45, 49, 55, 60mm.Packaging comes in bulk packs, net bags, cylinders, canisters, ...