X-Fibre .7 denier synthetic down is here, the smallest ultra-fine microfibers available.   This results in a lightweight insulation that is very compressable and warm.  X-Fibre micro-fibers are softer and finer than silk, creating a feeling smoother than down.  X-Fibre tears up the competition with an amazing 5 to 15X smaller denier insulation. You must feel the difference!