The 200G are just a little thicker than the Polartec. The 400G is twice as thick (surprise!). As you probably already know, it's the air in the fabric that keeps you warm, not the fabric itself. That is why the thinsulate is so great (and expensive)--it traps alot of air for the weight of the fabric, and it also rejects water so if it gets wet it still has air spaces and therefore warmth.
theskull
theskull
