You can use any yarn you like for this hat, and any hook size suitable for the yarn you wish to use, as this pattern is completely customisable!
I chose to use;
3 x Lopi Lettlopi yarn (aran/worsted weight) OR 3 x Sirdar Sublime Cashmere Merino Silk (DK/light worsted)
4.5mm crochet hook
Yarn needles and scissors
Pom pom maker
This pattern is in US terminology and is for all ages!
US sc (single crochet) = UK dc (double crochet)
US hdc (half double crochet) = UK htr (half treble)
ea = each
ch = chain