Like a down gilet - but without the down! The ROUTEBURN VEST is made entirely of synthetic materials.The STORMLOCK outer fabric is breathable, light and windproof - ideal attributes for active outdoor sports. The MICROGUARD SUPERLOFT synthetic fibre insulation has a similar lofting capability to down and a very good warmth-to-weight performance.It doesn't matter if the ROUTEBURN VEST gets wet, either, because it loses none of its insulation performance and dries out again quickly. The gilet can be layered up or worn as a standalone. In wet weather you can wear it under your hardshell.