Hydraulic rod seals shall be used to seal the fluid inside the cylinder block. JST offers a wide selection of piston rod seals to provide customers with the best solution to prevent external media from invading the system. The piston rod seal is installed inside the dust-proof seal inside the hydraulic cylinder end cover to prevent the hydraulic oil from leaking out. It is one of the main pressure bearing components. It is unidirectional pressure bearing and directly contacts with the hydraulic oil.