Challenge the deepest stabilizing muscles in your body while exercising on the unstable base of this Stability Ball™. Designed to improve balance and strength as well as tone your body, this Stability Ball is also used by Pilates enthusiasts as an office chair. Safety tested under 250kg (550lbs) of pressure. The Stability Ball ranges in size: 65cm (26”), 55cm (22”) and 75cm (29”). Sold individually, this Stability Ball is ideal for those under 170 – 185cm (5’7″ – 6’1”) tall. Note: For full inflation inflate ball, allow to rest for 2 days, and then complete inflation to ensure that ball is the proper size.