Gauge: 21sts in 4inches (10cm) in stockinette stitch, row gauge is not important in this case.

You will need:
DK yarn (up to 70 grams for the smallest size, up to 130 grams for the largest size), knitting needles to obtain the gauge (for knitting flat), two buttons, sewing thread, sewing needle, darning needle.
The hat is knit flat.