Aran weight yarn requires size 4mm to 5.5mm needle or crochet hook. If falls between Double Knitting and Chunky in weight. Also referred to as Worsted. Worsted is the American equivalent term used instead of Aran - both mean the same. Aran weight yarn was originally created for Fisherman’s jumpers and used when Double Knitting is not heavy enough and Chunky is too bulky. Perfect for outdoor or warm clothing and accessories.