Inflatable, anti-burst, quality-tested exercise balls in 4 sizes for men's and women's physiques:

45cm for under 5'
55cm for 5' - 5' 4"
65cm for 5' 4" - 5' 11"
75cm for 6' and taller

Tested 600 - 750 lbs for anti-burst durability. Exercise balls are a great tool for stretching, abdominal and oblique isolation training as well as for many weight training exercises. Available in bulk and packaged models.