This dual ball, trigger point relieving massage roller comes in 13 vibrant colors and measures 2.5" x 4.7". Made of sturdy silica gel, this is durable and long lasting and won't crack or tear. Perfect for post workout relief, these sit right along the sides of the spine to provide immediate relief from muscle spasms and soreness. These are great for your gym back, travel bag and to keep at home for an anytime personal massage at your fingertips.