X-Fibre .7 Denier Synthetic Down is here the smallest ultra-fine down X-Fibre clusters are blown into all X-Fibre synthetic down bags. This results in a down like appearance and lightweight warmth. X-Fibre micro-fibers are softer and finer than silk creating a feeling matched only by down. This is why X-Fibre blows away the competition at an amazing 5-15X smaller denier. We ask you to compare the feel it's simply incredible.