The Autumn Sky Cowl has been knitted in a Manos del Uruguay, Maxima yarn, called Ethnosphere. It is a worsted weight yarn. It’s exceptionally soft and luxurious. Any suitable worsted weight yarn can be used for this project, if you would like to make a yarn comparison with the Manos yarn before you purchase yarn or use yarn from your stash, look here, http://www.ravelry.com/yarns/library/manos-del-uruguay-ma..., I have knitted this cowl with a 6mm circular needle.