Composed of foam, the MB1 Massage Ball works to break up adhesion and stimulate blood flow, helping to ease joint and muscle pain and restore movementIdeal for targeting small muscles such as calves, piriformis, and pecsEncourages blood and oxygen flow to enhance overall movement, range of motion and performanceFoam surface is easier to clean and more hygienic than cloth2.5 inch diameter, weighs 1.2 oz., 1-year manufacturer's warranty