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