This fully reversible hat is double-layered and incredibly warm. It feels soft and light to wear, mostly because it is worked in a 4 ply yarn that has some very airy fibers (alpaca and possum mixed with merino). There is also a touch of nylon in this mix, which provides some stretch. I have used a variegated yarn and chosen a color in the same yarn for contrast, but you could use any 4 ply yarn. It would look just as effective in two plain colors.