Description Accessories Description Freudenberg Sealing Technologies (formerly Tobul) backup ring is a ring of hard, extrusion resistant material such as high nitrile, nylon, Hytrel, or PTFE. A back-up ring is designed to fit between the O-ring and the extrusion gap and prevent the extrusion of the O-ring. State of California Proposition 65 WARNINGCancer and Reproductive Harm - www.P65Warnings.ca.gov. Literature & Docs Accessories Freudenberg NOK Sealing Technologies 067AT20-60NA1F Piston Accumulator, 2000 PSI, 7.5 Gallon, 6.7"OD Freudenberg NOK Sealing Technologies 085A100-8N414 Piston Accumulator, 10000 PSI, 1 Gallon, 8.5"OD (Non-Code) Freudenberg NOK Sealing Technologies 067AT20-20NA1F Piston Accumulator 2000 PSI, 2.5 Gallon, 6.7"OD Freudenberg NOK Sealing Technologies 067AT20-40NA1F Piston Accumulator, 2000 PSI, 5 Gallon, 6.7"OD Freudenberg NOK Sealing Technologies 085A100-60N414 Piston Accumulator, 10000 PSI, 7.5 Gallon, 8.5"OD (Non-Code) Freudenberg NOK Sealing Technologies 085A100-20N414 Piston Accumulator, 10000 PSI, 2.5 Gallon, 8.5"OD (Non-Code) Freudenberg NOK Sealing Technologies 085A100-40N414 Piston Accumulator, 10000 PSI, 5 Gallon, 8.5"OD (Non-Code) Freudenberg NOK Sealing Technologies 067AT20-24NA1F Piston Accumulator, 2000 PSI, 3 Gallon, 6.7"OD Freudenberg NOK Sealing Technologies 085A100-24N414 Piston Accumulator, 10000 PSI, 3 Gallon, 8.5"OD (Non-Code) Freudenberg NOK Sealing Technologies 085A100-12N414 Piston Accumulator, 10000 PSI, 1.5 Gallon, 8.5"OD (Non-Code)