This SAE Aerospace Standard (AS) specifies scarf-cut polytetrafluoroethylene (PTFE) retainers (backup rings) for use in glands in accordance with AS4716. They are usually used in hydraulic and pneumatic system components as anti-extrusion devices in conjunction with O-rings and other seals for static and dynamic applications. NOTE: This specification includes material tests but does not include hydraulic or pneumatic performance tests.