Exceloft insulation uses 8-denier polyester threads as a structure to intertwine with extra thin 0.7-denier threads that add more air pockets and resilience. As a result, Exceloft products rival the warmth and weight of down products. Exceloft excels in wet conditions: because the fibers used in Exceloft retain less than 1% of their weight in water, Exceloft will keep you warm even when wet.