Gas springs are designed in a similar fashion to shock absorber struts. They are made up of a chamber tube, piston, piston rod and end fittings.

The chamber contains highly pressurized nitrogen gas which forces the piston rod to extend. The gas pressure is set during manufacture to obtain the correct spring force depending on, for example, the weight of the rear hatch.

As the spring compresses there is less volume in the tube, forcing gas through valves in the piston and thereby increasing the suspension.

The gas spring contains some oil to lubricate the seals, piston and piston rod. The oil also provides a damping effect when the spring nears full extension.