I hike and am a very serious amateur photographer, who prefers landscape photography. I've been using a six-year old Mountain Hardwear Nitrous jacket and it's great, too, but requires many layers underneath to stay warm. Not so with the Kelvinator. I recently hiked in a local park during a snowstorm and had on a long sleeved cotton t-shirt, a MH stretch zip lightweight fleece shirt and the Kelvinator and had to unzip the Kelvinator because of how warm I was.The thing I really like about the jacket material is where the Nitrous' material really has no moisture management, but the Kelvinator's outer shell repels water pretty well. If you're out for a long time in cold, rainy weather or snow for a long time, it'll eventually get a little wet, but the advances MH has made with the shells is impressive.I'm 6'4", weigh 235 lbs and the XL fits me to a "t."Good stuff, folks.