This resistance shaft is also called a torsion shaft. The maximum torque of the product itself is slightly smaller than the torque of the shaft. If you apply a little force by hand to make the torque greater than the torque of the shaft, it can rotate. As soon as you release your hand, since the maximum torque of the product itself is slightly smaller than the torque of the rotating shaft, it stops again. This is how a torsion pivot works.