Granite Gear Aquatherm & Aquasack
Here's what other sites are saying:
The Aquatherm from Granite Gear is an insulated bag that completely surrounds a standard 32-ounce Nalgene bottle with half-inch foam and a reflective insulation material. These sacks help prevent water from freezing while winter camping or mountaineering. They also work great for keeping hot drinks hot in the winter and cold drinks cold in the summer.