Buffer Seals protect the rod seals by reducing pressure peaks. Abrupt pressure peaks can occur by external forces acting on the piston rod, initiated by the fluid inside the cylinder. These pressure peaks can be far in excess of the system operating pressure. Buffer Seals in combination with Rod Seals provide an effective rod sealing system for cylinders in heavy duty applications at high temperature and pressure. 
RBB
RBB Buffer seal with polyurethane sealing ring, integrated anti-extrusion ring; designed to vent pressure back to system side; improved gap extrusion resistance at abrupt pressure peaks; fits narrow grooves; suitable for heavy duty applications (metric and inch).
S9B
S9B Nitrile rubber O-ring energizer, PTFE slide ring; also available with polyurethane slide ring to improve wear resistance and ease installation (metric and inch).
RSB
RSB Buffer seal with PTFE slide ring, nitrile rubber energizer; patented and improved design to reduce pressure peaks acting on the rod seal and vent pressure back to system side; improved gap extrusion resistance at abrupt pressure peaks; suitable for heavy.