Babs, I helped develop the 46 Rail line. I used it extensively this fall on 3 hunts (so far). My hunts were in temps from the 60's to over 100 degrees. The fabrics breath well and the stretch and cut is unmatched. I did just talk with a buddy that just got back from South Dakota hunting. He was there when the blizzard hit, hunting in temps from the 30's on up. He said with a base layer, it performed really well for him. It is quite different from both Sitka and Kuiu. You might ask Cade for his opinion, he has been wearing it for whitetails this fall.