The principle is that there is a magnet near the periphery (or inner periphery) of the metal flywheel to produce resistance. By adjusting the distance between the magnet and the metal flywheel by pulling the wire with the human knob, the resistance can be adjusted to meet the requirements of different exercise intensities. Can effectively prevent hypertension, obesity and arteriosclerosis, and make bones strong; Combined with the hand rope, you can do rowing and exercise your arm muscles.