I can elaborate a tad for Bryce...
A lot of people walk up to the Kelvin pieces and brush their finger against it. It is loud. Well, it is not supposed to be worn as an outer layer. The same material that makes it loud also makes it slippery. When you put any of the layers over it, as you are supposed to and as you must do to use it properly, a 90% Jacket, Ascent Jacket, Stratus or Celsius Jacket slides like hot snot on a cold platter :D . That gives a SILENT combination with a freedom of movement like you are out shooting in your Tshirt. It is very hard to explain to guys used to wearing bulky wool that grabs at each other on each layer and pulls against itself. I guess I am just young enough to not be so stubborn I can't try new things and admit when there is a better mousetrap. I've got a closetfull of top end wool. I own no warmer jacket than the Kelvin, it weighs about the same as a can of pop and packs down to the size of a Naglene bottle.
I am sure Bryce has more, AND can paint a better picture, but he is probably in the middle of molding young minds right now :D