FKM O-ring 520 x 7mm (OD 534mm) 80 Shore A | Tameson.com
BUSY-CORNER 382 Pieces FKM O Ring Kit, Fluorocarbon 75A, 30 Inch Sizes, Chemical Resistant and Oil Resistance O-Rings for Various Chemicals, Hydraulic, Cylinders, Plumbing (Yellow Box, Brown Orings): Amazon.com: Industrial & Scientific