From the book:

“Inspired by Dr. Seuss’ wonderful characters, the Whos, this whimsical hat makes an adorable and unique baby gift. It’s worked in a wool/acrylic blend yarn that is soft and easy to care for, with a touch of nylon to make it durable. It incorporates a fun and unique tassel which is worked from side to side, then stitches are worked around the bottom of the tassel, and the hat is worked in the round from the top down.”