Abstract: A shock absorber includes opposing first and second cylinders and first and second pistons disposed in and cooperating with the first and second cylinders to confine first, second and third chambers thereamong. The second and third chambers are filled with a damper-fluid. The second piston is formed with first and second down-flow channels and an up-flow channel for permitting up and down-flows of the damper-fluid between the second and third chambers. A hollow shaft extends in the first and second cylinders and is formed with an opening for permitting the down-flow of the damper-fluid via the second down-flow channel. A damping adjusting rod is mounted in the shaft and is movable in an axial direction to a first axial position, in which, the opening is blocked by the damping adjusting rod, and to a second axial position, in which, the damping adjusting rod moves away from the opening.