When you have just opened a bottle of wine, oxygen in the air reacts with compounds in the wine to release its aromas and flavors. But while oxygen brings out wine's characters, it also alters it with prolonged contact. So if you just want a glass or two, but don't want to have to finish the bottle; or you have a few bottles you'd love to taste, you'll need a wine preserver to keep the unfinished wine fresh.
Winesave is made of 100% argon gas, a non-toxic colorless, odorless, tasteless inert gas that is denser than oxygen, and therefore stops prevents wine from oxidation.
Just squirt for one second into your unfinished bottle of wine, and re-seal the bottle with a stopper or a screwcap.