From the Website:

Skill Level Easy

Shown in size 22” in Sirdar Peru, 19” in Black Forest Naturwolle, and 23” in Nashua Handknits Wooly Stripes.

Needles Any appropriate size for the yarn chosen: set of 4 or 5 double-pointed (dpn) and 16” circular (cir).
Notions Markers (m); waste yarn; safety pins or removable markers; stitch holder; tapestry needle; pom-pom maker (optional).
Gauge Any gauge that produces pleasing St st fabric with your chosen yarn and needles.