It was -20 celsius and all I wore in the bag was my toque, merino long sleeve top, merino long johns and mohair socks. The end of my nose was the only part of me that was cold in the morning. Best danged system for the money known to date. BTW I have over 40 years experience with backwoods camping plus was a certified Outward Bound leader.
This review was written in the old system and had content requirements that are different than reviews written today.