This pattern calls for two different weights of yarn to be used simultaneously. Ravelry doesn’t support this yet, so the details will have to be in the notes. The yarns called for are:

1 - 75 yards of Bulky weight yarn with a gauge of 12 to 15 stitches in 4 inches/10 centimeters.

1 - 75 yards of Worsted weight yarn with a gauge of 18 to 20 stitches in 4 inches/10 centimeters.

It’s also worth noting that this hat is knit flat, and seamed up the back.