Neoprene-70 O-Rings - AS568A Aerospace Standard ID: #   -018

7/8" OD - 3/4" ID - 1/16" Thickness  - 100 per package

Neoprene is a more durable material than standard Buna O-rings.  Neoprene does not "dry rot" as easily as Buna-N.  Neoprene costs more than Buna-N but the additional cost is well worth it.

The #018 o-ring is typically used for ID glands in the barrel (where the gland is inside the barrel bore and not on the keg tenon, but can be used either way.  The small cross section of this oring allows for a shallower gland, but also means there is less material for compression and requires a bit more accuracy with mating parts.