Variable density acupressure balls. .Hard, medium and soft densities allow users to duplicate the precise work of therapists/massage. Excellent to take in the car or onto to plane to treat hips and upper back against the chair/seat. 66 mm diameter Includes: - 1 soft acuball (yellow) - 1 medium acuball (orange) - 1 hard acuball (red) - laminated acupressure chart