plow & hearth pavenex fireplace blanket stops overnight heat loss (medium 42" w x 32" h) plow & hearth place this fire-resistant blanket over the outside of your fire screen at night to keep warm air in and to block out the cold. it conserves energy and saves money by reducing the heat loss that escapes up your chimney after a wood burning fire. made from pavenex, a fire-resistant carbon fiber material. heavy-duty magnets attach it to your metal screen. made in usa.