Global O-Ring and Seal on X: "Requesting for backup? We have backup rings readily available in NBR, Viton, and Teflon (Solid, Split, and Spiral versions). Use our Backup Ring Size Chart here
Back-up Rings for Oil & Gas Applications - Trelleborg
What are Back-up Rings/Anti Extrusion Rings Guide - Barnwell : Barnwell
8-330/U - 2-1/8'' ID X 2-1/2'' OD X .055'' High Backup Ring (4 Pack): Amazon.com: Industrial & Scientific