1.The shock absorbing capability can be adjusted by the adjustable device when the shock speed is changing. 2.The spring can reset the piston rod fast cause the perfect movement of the check valve. 3.It adopts horniness chromeplated piston rod, special sealing element; it can have a long and stable efficiency. 4. It adopts fittings, such as orientation stop screw cap, setting nut, retaining plate etc. 5. The nonstandard can be also manufactured.