I put this bag to the test on an overnight on the AT. Temps were to be in the high 20's but managed to dip down to 19. The bag performed great. I started out with too many layers on and eventually got so hot I "Winnie the Pooed" it (shirt only, no bottom)! About 2 a.m. I did put my socks back on and a Terramor base layer on bottom, a pair of Carhart pants over top and a long sleeve polyester top and short sleeve poly over that. I love the option to put my arms out the sides. This made it so quick and easy to move and adjust things inside the tent. That is the best part about this bag. The only thing i did not like was that when you have the zipper pulled all the way up it doesn't have a place to tuck in and hide. It's a cold metal zipper right there touching your face and in the way. I think I will try and cover it somehow. Maybe like with fabric or tape or something. Can't wait to get out again! Highly recommended down bag.