6 x 12 inch, Round, Black. Perfect for positioning, balance, postural and muscle re-education, spinal stabilization, body awareness and coordination, and ranging and strengthening activities. Round rollers offer progressive exercise sequences - user can move from an easier (smaller diameter) to a more difficult (larger diameter) roller. Half round roller is a great tool for ankle stretching and knee rehabilitation. Use half roll as rocker board by standing on flat side. Diameter refers to the width of the half-round profile. The ethefoam rolls and half rolls are strong enough to be used by large adults and active children. Foam rollers can be used alone or with other exercisers such as exercise band, tubing, weights and balls. Standard white rollers - in every size, including the newest extrasturdy, jumbo 8” diameter! TufCoat foam rollers for washability, firmness, and durability. Blue foam rollers to conceal dirt and wear. Premium EVA foam rollers for a more firm feel. The new black, high-density foam rollers offer more durability than the white rollers at an economical cost.