With all the modern materials turning up we are starting to forget the old and reliable way of dressing for outdoor life. Techniques which our ancestors used in everyday life while working in the forest, hunting and harvesting are in many ways far more efficient and reliable than the clothes used nowadays. The three layer system The three layers are the base layer , used to wick moisture (sweat) from the skin, it is worn closest to the body. The mid layer which is your insulation. And the outer shell , which protects you from the weather. They all serve very important roles in your heat regulation. The genius thing about the three layer system is that you can remove just one layer to regulate heat and adjust for the weather. On a warm but rainy day you can skip the mid layer and just use the base layer and the shell. On a calm but cold day you may just need the base and mid layer for maximum ventilation. Also, when you are moving fast by biking or using some vehicle it's g...