It's a Pom Pom Pom Pom Beanie!  CatStronaut Pom Pom is embroidered on the hat's front cuff, and the New CatStronauts Logo is embroiled on the back.  The best part is, you can choose to wear the hat anyway you want!

Hats are 100% acrylic.

One size fits most. (But, it seems like the blue hat is a slightly snugger fit.)