Steel. Retracted Length 12″. Approx. Stroke 7.68″. Extended Length 20″. Output Force 30 lbs. Shaft Diameter 6mm. Socket End Style. The ideal solution for lifting, lowering and counterbalancing weight. The gas spring is a self-contained, nitrogen-driven counterbalance product which provides uniform handle forces, non-catastrophic failure and many years of service. Because energy is provided through gas pressure, our gas springs give you repeatable, unvarying performance which is superior to mechanical, spring or damper type products.