As compared to coil springs, gas spring has an extremely flat, nearly linear characteristic curve, which facilitates uniform comfortable adjustment or pivoting movement. Also, its another advantage over mechanical spring , is damping . When gas spring is installed piston rod facing downwards, during extension it first travels through gas portion & then through oil portion. The oil dampens the movement & reduces the speed considerably. However, the extension speed & damping characteristics can be adjustedas per applications requirement.