Textured surface of ball for easy grip. Balanced, uniform weight. Constructed with rubber to bounce. * Color-coded to easily identify weight. Tan (1 lb), Yellow (2 lb), Red (4 lb) are 8" diameter * Green (7 lb), Blue (11 lb) are 9" diameter * Black (15 lb) is 10" diameter * Silver (20 lb), Gold (30 lb) are 11" diameter