I've wrapped my UDS in this stuff for smoking in winter:
It came in a roll 24"x25' and i bought it at Home Depot. I looked on their website but didn't see the product. It was in the aisle where you would buy the blankets for water heaters. I've smoked food in the winter as cold as 20 degrees Fahrenheit and was able to keep the temp steady at 275 for 8+ hours.