In newborn, 0-3m, 3-6m, 6-12m, 12-24m, 2-4yr, 4-6yr, 6-12yr sizes

Gauge: 21 sts in 4in/10cm in stockinette stitch
You will need yarn (up to 90 grams for the largest size in main color and small amount in contrast color), knitting needles to obtain the gauge, a tapestry needle to weave in the yarn ends and to sew the back of the bonnet. A crochet hook, if you are making crochet ties.
Since the hat part is knit flat, you can use any knitting needles you like. I prefer using ether long circulars, or long straight “afghan” knitting needles.