Shocks and Struts not only provide a comfortable ride, but improve the control and handling characteristics of your vehicle, which would otherwise continually bounce off the road, making driving, steering and braking extremely difficult. Shocks and struts are designed to help keep your tires on the road, and also control the spring's action to resist the car bottoming out, especially after driving over (through) a pothole.
Shocks provide resistance by forcing an oil through small valves in the piston as it tries to move up and down with the springs. Because the oil cannot be compressed, and only a small amount of fluid flows through these valves, the shocks create resistance to the spring's and vehicle's movement.
Premium shocks and struts have replaced air in the shock with pressurized nitrogen gas, to prevent bubbles from forming in the hydraulic fluid. This make the shocks' resistance more consistent and quickens the response of a shock to improve comfort and control.