Buffer seals are commonly used in combination with another rod or piston seal, typically a U-cup style seal. Buffer seals in rod applications are designed to absorb pressure fluctuations when working under high-load conditions, this increases the lifespan of a rod seal.
See buffer seals literature for more information.
Buffer Seals Profiles

R
Imperial

HBY
Imperial

RS
Imperial

Caterpillar Equivalent Style - One Piece
Imperial

Caterpillar Equivalent Style - Two Piece
Imperial

MR Style
Metric

MR with pressure Relief Port (PR)
Metric

S Style
Metric