A Bottle Roller is not only a foam roller- it also helps keep your drink warm. After about an hour, a Bottle Roller keeps your Nalgene* about 8-9 degrees warmer than no cover (the "Naked Nalgene" in the chart below).
As the weather gets colder, keep your drinks warmer with a Bottle Roller!
*This is an affiliate link, so Bottle Roller gets a share of any Nalgene purchases you make through this link at no extra cost to you.