The Thera-Band SDS® (Slow Deflate System) Exercise Ball is made from a specially formulated compound that enables the ball to resist the tendency to burst when punctured. The SDS® Exercise Ball consistently provided 8-10 minutes of gradual deflation time when punctured under a constant load of 250 lbs. The SDS® Exercise Ball is available in four sizes to accommodate users from 4'7" to 6'8" tall. The sizes are distinguished by the Thera-Band proprietary color-coding system. A new full-color, instruction guide with the most up-to-date exercise positions is included with each SDS® Exercise Ball. It illustrates correct positions for 24 exercises designed to increase flexibility, improve coordination and strengthen the abdomen, back, chest, arms, thighs, legs and buttocks. Uses for the Thera-Band Ball include: exercise, gym, balance, fitness, yoga, pilates, resistance and stability! Pump not included.