Before selecting a size, we would advise to measure either the users inside leg length, or arm length, and compare it to the ball diameter. This should give you a good indication of how the user will interact with the ball.

Sizes (dia x length) :

Petite - 30 x 50cms

Small - 40 x 65 cms

Medium - 55 x 90cms

Large - 70 x 115cms

X large - 85 x 130cms