Size Regular (16 -18 ) * The Theratrac gently stretches neck muscles allowing the vertebral discs to realign freeing the nerve root tissue from the pressure of the discs * The Theratrac helps locked neck muscles to slowly stretch and relax allowing misaligned vertebrae to resume their normal supportive position * The Theratrac cradles the head and neck via a curvature in the neck portion of the device as well as a special head rest section that is vertically pneumatic * 5 year limited warranty Both the headrest and neck region inflate with over 30 lbs of adjustable pneumatic pressure to create traction in the cervical curve