SKIN LAYER

Can't be itchy, but sadly there's no rule on not allowed to be smelly and I tell you the synthetics get really smelly! Wool's not so bad.

INSULATING LAYER

Must maintain warmth even if wet. I was taught 'Cotton Kills'. It is cold when wet and takes a long time to dry, so no cotton on a mountain.

SHELL LAYER

Is windproof, waterproof and breathable