The GAMMA Quick Kids 36 Foam Ball is USTA Approved for 10 and Under Tennis. Ideal for ages 8 and under on a 36′ court with the 10 and Under Tennis or Tennis 10’s format. 75 percent slower speed than a standard tennis ball.The Quick Kids 36 Foam Ball bounces lower than the Revolution foam ball so it is ideal for very young children. Two-tone surface helps to learn and practice spin. USTA/ITF Stage 3 specification.