Gymnic red heavy-duty, 34 in (85 cm), roto-molded vinyl therapy ball. Each is precision roto-molded without seams. They're brightly colored and have raised latitudinal ribs that make them easier to hold onto during balance training, stretching or strengthening. Therapy Balls are ideal for home exercise programs. Physio-Gymnic Balls are built so tough, they've been rated to safety support 300kg (661 lbs.).