ARCTIC SHIELD ECHO SLEEPING BAG LINER WINTER MOSS UNIVERSAL Arctic Shield Echo Sleeping Bag Liner features Retain heat retention to lock in heat down to 50 degrees, durable polyester outer shell, polyester silk lining, contoured hood and mummy shape. Use inside your sleeping bag for added warmth. Helps prevent wear and tear on your sleeping bag. Includes stuff sack for easy repacking, transport and storage.