Back-up rings are the most common anti-extrusion devices employed in dynamic and static sealing, designed to prevent the migration of sealing material into the extrusion gap under the system pressure. Parker offers a wide range of back-up ring geometries and materials to suit every seal type and application. They are open or closed shapes for snap assembly made of a broad range of compounds which are highly resistant to thermal or mechanical stress. Parker back-up rings help reduce costly downtime and ensure long-term functional reliability.