Friction in one direction only: HG-TQA90-A: free rotation when turned counterclockwise, constant torque is applied when turned clockwise. HG-TQA90-B: free rotation when turned clockwise, constant is applied when turned counterclockwise Note: Initial torque may vary – 20%~ + 40% Not suited to vibration environment Torque will be affected by temperature Not suitable for high frequency use Do not lubricate For indoor use only