Bilstein's technically superior, patented monotube gas charged design allows the excessive heat from the oil to transfer to the outer surface of the shock body and dissipate more efficiently. The dividing piston also permits the oil to expand as heat builds, preventing aeration (foaming) and viscosity loss. This allows the shock to maintain full damping characteristics as temperatures rise.The tube of a Bilstein Gas Pressure Shock Absorber is fabricated using a special extrusion method. This process achieves an extremely tight peak-to-valley tolerance and maintains consistent wall thickness. Bilstein's seamless monotube design provides superior tube strength while maximizing heat dissipation and shock life.The piston head design allows independent tuning of the compression and rebound damping forces to provide optimum ride comfort and performance without compromise. It features fewer parts than most conventional twin tube and so called road sensing shock designs. This simple, yet exceptionally functional digressive design contributes to the extreme durability and long life of Bilstein Shock Absorbers.