The gas spring plays a supporting role. According to the structure and function of the gas spring, the gas spring mainly has free gas spring, self-locking gas spring, random stop gas spring, traction gas spring, damper and so on. The product is widely used in various fields. ft the spring, can be divided into can be self-locked gas spring (such as the bottom of the seat lift, after the boss chair back of a chair, etc.), not self-locking gas spring (such as car tail box, a built-in wardrobe or cupboard door lifting support，car tailgate gas struts), the structure of the gas spring is mainly composed of sleeve, piston and piston rod, adding high pressure air or high pressure nitrogen gas inside the sleeve, Due to the difference in area between the two ends of the piston, the piston and the piston rod are pushed to move and support people or heavy objects