John S, I'm not worried at this time about O2 permeability, but rather the ability to reduce O2 in the headspace at the time of sealing the bottle. When a cork is pressed in, it compresses the atmosphere in the headspace, and that atmosphere has no choice but to dissolve in the wine. If it has O2 in its composition, that is highly soluble and reactive in wine. If it is just nitrogen, it simply pressurizes the bottle's headspace due to its low solubility, and could contribute to leakage. Standard practice to avoid such possible problems is to inject some nitrogen immediately before corking, then pull a vacuum on the headspace as the cork is going in, hopefully creating a headspace that is little different in terms of pressure from the outside atmosphere (neither promoting leakage in the case of high headspace pressure, or sucking air back through the cork in the case of negative differential pressure. I am unaware whether the automatic vino-seal applicator has any sort of vacuum during the application (not to mention nitrogen or argon injector), but the Otto Sick unit doesn't look as if it has such facility, so I wondered about O2 pickup during closure application. If there is no method of mitigating positive pressure or O2 pickup, but it proves not to be a problem, might as well just apply the Vino-seals by hand.