Gauge: 21 sts in 4 inches (10cm) in stockinette stitch. The row gauge is not important for this pattern.
Please make a gauge swatch! If you are just trying to wing it and go by the recommended needle size only, the chances are you may end up with a wrong-sized garment that you put a lot of work into making!
You will need: DK yarn (up to 100 grams for the largest size, up to 90 grams for 5+sizes, up to 80 grams for 2-5yr size, and less than/about 70 grams for the smaller sizes), knitting needles to obtain the gauge for knitting in the round (please make sure you make a gauge swatch!), darning needle to weave in the yarn ends. One stitch marker.
This cowl is knit in the round.