Flexibar takes little space and does a lot in spinal disorders (vibration activates and trains the small intervertebral muscles that are important for the Stabilitität WS) Disadvantage: MATERIAL PROBLEM: after a few weeks, the surface of the fiberglass rod is cracked and split off tiny needles, which can penetrate into the skin on contact as fine cactus spines. Wrap with tape helps, but it's not really meant