A mono valve is a valve with 1 connection point. A double valve has 2 connection points. A second connection can be fitted with a single valve with an extra port or with a lateral valve. A lateral valve is used for double set set-ups. You will always need a left and right valve with a manifold.
Working pressure of the valve. Note that the cylinder needs to have the same working pressure!
Standard O-rings are suitable when using air. Viton O-rings are used when diving with Nitrox- Enriched air. However, they can also be used with air. Viton O-rings are generally recommended.
