## Trimix family : Normoxic Trimix Normoxic trimix, as you may guess, is prepared with a normal proportion of oxygen. It is one of the three kind of [Trimix](Trimix.md). Concentration : between 18% and 21% of oxygen, between 20% to 24% of helium and ~55% of nitrogen. We also can adjust the concentration and even get rid of the nitrogen to create what we called a "[Heliox](https://en.wikipedia.org/wiki/Heliox)" mix which consist of 21% oxygen and 79% of helium. This one is breathable on the surface and give the ability to dive in the -40 m to -60 m zone.