Its characteristic is that it can be rigidly locked in the stretching direction. Due to the small gas space and small compressible range, the locking force in the compression direction is relatively large. The elastic ratio can be adjusted according to the change of the position of the floating piston. The disadvantage is that for a certain length of cylinder body, the stroke is relatively small and the ratio of stroke to cylinder body is relatively large. It can be applied to any mechanical mechanism that requires angle adjustment, vertical height adjustment, or horizontal adjustment and at the same time has rigid locking in the stretching direction or has a relatively large locking force in the compression direction. The two ends can be connected in multiple connection methods.