This helps keep any extra air out of the bottle as you use Longitude. Depress the nozzle for about 3 seconds. You can use a little more gas for expensive wines, or if less than half the bottle is remaining.

Longitude works by laying a blanket of Argon - a safe, naturally occurring and inert gas - over the surface of the wine, drastically reducing spoilage caused by oxidation. 

When you open a bottle of wine, oxygen in the air immediately starts to react with the contents, starting a rapid chemical reaction known as oxidation. For older wines, this opens up the full flavour and bouquet of the wine, but for younger and lighter wines this rapidly becomes too much of a good thing. The number one trick to preserving wine is to keep out unnecessary air until the wine is actually in the glass.

Using Longitude will keep your wine fresh from one occasion to the next.