A shock absorber comprises a sleeve, a cylindrical piston with a seal attached to the cylindrical surface of piston with two side surfaces, a rod coupled with the piston, a piston cap enclosing the sleeve on the piston's side, and a rod cap enclosing the sleeve on the rod's side. The piston and rod move within the sleeve overcoming resistance of oil/gas cross-flows from one sleeve's chamber to the other, friction between the seal and the sleeve's walls, and friction between the rod and a seal mounted in the rod cap. The proposed absorber allows increasing the resistance offered to the movement of piston thereby improving the efficiency of damping, and suppressing/avoiding auto-oscillation and resonance regimes. This is achieved by providing a number of narrowing/widening necks arranged on the sleeve's walls within regions adjoined to the caps. Different embodiments combine features conditioned by various diameter differences for the necks, etc.