Hydro-pneumatic gas springs are suitable for lifting, counterbalance, damping effect purposes. They have a lot of advantages over traditional mechanical springs, some of which include: speed curve selection (linear, progressive, and regressive), easy installation, lockable at desired position, damped motion, etc. Gas springs consist of a tube, filled with compressed nitrogen inside, and a piston rod with piston assembled on it. Internal pressure, created by compressed nitrogen acts as a force in extension direction when the rod is pushed inside the tube. The charged amount of nitrogen depends on required extension force and application requirements. Gas springs are usually installed with piston rod pointing downwards to maximize damping effect and lubrication of inside parts.