The oil within the cylinder, when it is compressed or extended, moves from one side of the piston head to the other, providing a damping effect. Removal TIP : it is very easy to replace most gas springs / shocks/ struts, the most common connection used is the nylon “ball joint socket” to remove your old unit simply insert a “flat” blade screwdriver under the spring clip (you do not have to remove the clip) using the slot provided in the back of the socket, push the screwdriver down just a bit this causes the spring clip to open and it will release the ball end.