Amazon Portable Emergency Blanket & Bivvy Sack Thermal Sleeping Bag - 2 Pack $13.52 @Amazon

[BlueMarigold]

The noise is kind of annoying, but the warmth makes up for it. Anyone tried doubling up with a wool blanket for extra insulation?

 

[BlueHarborTea]

That matches my experience—stayed warm even when temps dipped below freezing. Has anyone tried doubling up with two blankets for extra chill, or is that just overkill?