The only cold weather gear I ever used was an Army "Artic" sleeping bag,and I LOVED that thing. I had just came back from a couple of years on Okinawa,where everybody grabbed coats and gloves when the temps dropped into the 60's,and was sent on a training exercise in the mountains in December. Record cold. So cold the sap in pine trees would freeze at night,and some would explode after the sun came up and hit them. There we were sleeping on the open ground with only an air-mattress under us,and no cover over us.
The way to get the warmest was to crawl into one naked,and use your folded up uniform as a pillow. You would be as snug as a bug in a rug,but it was painful to even think about climbing out and trying to get dressed in the morning.
It was this training mission that convinced me to volunteer for VN. Say what you want,there was no danger of freezing to death in VN. Not even in the mountains.