Gas struts are used when flaps or components need to be pushed, pulled, lowered or lifted by hand without external energy. They are maintenance-free, ready to install and available ex works. The gas springs are individually filled to a specific pressure in order to achieve the desired nitrogen filling on the side of the piston rod when the piston rod is pushed in and thus achieve the correct increase in force. The increase in force depends on the ratio of piston rod diameter to cylinder diameter and is approximately linear.