Marpac Gas Spring Hatch Lift - 12 Inch Retracted - 20 Inch Extended - 90 PoundsThe 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. Stainless steel. Socket End Style. The ideal solution for lifting, lowering and counterbalancing weight.