Oversized soft foam learners balls, USTA approved Excellent durability and performance, Ideal balls children learning the game good Quality soft foam, Designed for 36" courts, driveways and playgrounds These Wilson Shortex tennis balls are constructed from foam. Measuring 8.5cm in diameter, they are perfect for toddlers just starting out playing tennis. The design has given them a hard wearing outer, to ensure the balls are able to withstand many hours of being hit, with a racket. These foam balls come in a handy drawstring, plastic carry bag. Each bag contains 12 Shortex balls which are suitable for use indoors and out.