High Performance Style 590 Back-up Rings feature exceptional strength and abrasion resistance along with a 53 Shore D hardness rating which makes them suitable for high pressure service where extrusion is a problem. Primarily used as a u-seal back-up, these rings can be used with o-rings. They also retrofit urethane and PTFE back-up rings, with greater performance characteristics. 'S' suffix designates a split ring.
