Rock freely back-n-forth to help stimulate foot and leg circulation or lock in place for firmer support. Prevents back and leg discomfort by ensuring the correct posture is adopted. Built-in Microban? protection fights the growth of harmful bacteria for the lifetime of the product. Adjust position using foot pressure and it remains in preffered position until you wish to readjust. 17-7/16" W x13"D x 4-1/8", 4-7/8" or 5-5/8"H. Black/Silver.