The stretchiness of the ear warmer means this is a great crochet ift idea If unsure of the actual size.
Use any hook and any yarn as long as you use the measurement guides to make to the size required

YOu can find all of my FREE headband crochet Earwarmer Pattern HERE https://crochet-patterns-free.com/earwarmer-headband-croc...

Or Buy hte AD free Pdf right here on Ravelry