Filled my stanley the other morning at 6am with fresh coffee out of my french press and had a few cups on my drive. This particular day happened to be -15 below here in Wisconsin with wind chill. When I arrived at my destination, I left my thermos in the car and went about my business. That stanley sat in the vehicle in the -15 temperatures for over 7 hours. I know they are rated to keep liquid at a desirable temperature for a quite a while but this was kind of an extreme situation. When I got back to the vehicle, curious as to the coffee, I cracked it open and poured a new cup. To my amazement steam poured right out of its lid. No words were needed other than a celebratory drink.