Extra layers are for those who need extra drag without having a looser fit.
If you have decided you need some extra layers, then you next need to choose what kind and where.
Generally, the first place layers are added is the legs, then the arms.
Layers are offered in three fabrics: Taslan, Ripstop Nylon, Cordura. The three available options increase in power, but also get hotter and slightly less comfortable.
The Taslan layer is the less noticeable and gives you the less drag of the 3 options. Nylon gives you decent drag and is not bulky but doesnt breathe as its like your canopy material. Cordura gives you the most power and drag.
Taslan and Ripstop Nylon are added under your main layer, while Cordura is added outside.