These are listed as each, if you want 2 sets you would order a quantity of 4.
AFLAS is a long-life material suitable for wear resistance needed on the piston.
Cross Section: Round
Nominal Dash Size: 111
Durometer Rating: 80A
Actual Outside Diameter: 0.625″
Actual Inside Diameter: 0.424″
Temp Range: -14°F to +428°F
Any 111 O-Ring replacements can be used, but depending on material and Durometer rating (hardness) will depend on their life. Regular O-Rings (usually nitrile or Viton material) will also work, but you may have to replace them more often or lubricate them with a food-grade grease more often.