The Therm-a-Rest Regulus Blanket partners with your mattress to create a sleep system offering excellent freedom of movement and temperature regulation in temperatures as low as 40F (4C). Synthetic eraLoft insulation offers warmth and loft that performs in all-weather conditions. A shaped footbox and insulated baffles create a secure connection with your mattress and prevent drafts. The included loop kit allows your blanket and mattress to function as one throughout the night.