Unlock twice the relief with the MB2 Roller. Designed with two settings to ease tight muscles and stiffness in the neck and back, the MB2 Roller can support proper posture and upper back mobility. The adjustable length can be locked for use on smaller muscles that attach directly to the spine, or extended to target the larger muscles of the back. The massage balls use a patented, layered construction made up of different densities. The unique EVA foam compresses to grip the tissue, encouraging blood and oxygen flow to keep muscles and fascia healthy. Double massage ball design with patented, layered EVA foam surface encourages blood and oxygen flow to keep muscles and fascia healthy Adjustable length can be locked for use on smaller muscles around the spine, or extended to target the larger muscles of the back Helps stimulate circulation, increase mobility in the spine, and improve posture Foam massage balls offer optimal compression and pressure for safe, effective and targeted self-massage Highly durable, water resistant, and easy-to-clean 9.5 x 4.3 x 2.6 inches, 0.24 pounds / 109 grams