Resist-A-Ball Stability Exercise Ball Kit With Resist-A-Ball, you'll add challenge to your workout while improving posture, core strength, balance and flexibility The Resist-A-Ball is burst resistant with raised ribs for improved grip and a recessed inflation point Includes exercise wall chart, foot pump and measuring tape 65 cm ball generally works best for users around 5 ft 8 in to 6 ft 1 in tall; user capacity: 800 lbs