Wait another month to pull out your winter jacketcastelli39s design team first came across polartec174 power stretch fabric when using outdoor kit while hiking in the dolomites they thought this could be an excellent fabric to use for cycling kit its luxuriously thick and warm and the exceptionally tight knit of the fabric keeps a lot of the wind out yet it lets enough air come through to prevent overheating and keep you dry working with polartec174 they gave it the hard face fini