A Filson double Mac uses two layers of wool over the arms and shoulders. A single Mac uses one layer of slightly heavier wool. I have a single Mac that I love, but it rarely gets cold enough in CA to wear it.
Tin cloth doesn't breathe quite as well as Goretex, but you'll go through a dozen Goretex jackets before you'll wear out a Tin cloth. Filson also makes lighter weight waxed cotton clothing called Shelter Cloth and Cover Cloth. Shelter cloth is lighter than Tin cloth, but is what many others would still call heavy duty. For the max flexibility, use Cover cloth. It's not quite as indestructible as Tin cloth, but still wears well.
http://www.highlandhiker.com/Filson-Fabrics-sp-8.htmlFilson is expensive, but worth every penny. Your grandkids will be still be wearing it decades from now.
