Montbell Seamless Alpine Burrow Bag #2 Long - SunflowerThe Seamless Alpine Burrow Bag is made using Montbell's proprietary synthetic insulation, Exceloft. Exceloft offers advantages in wet or humid conditions that could potentially compromise a down sleeping bag. EXCELOFT is perfectly paired with our seamless construction, which reduces sewing holes where warm air can escape and create a more airtight sleeping bag. As a result, this simpler method of construction allows Exceloft to loft to its fullest