From the Knit Picks Website:
This chulo, adapted to modern styles and tastes, includes a geometric motif. The colorwork keeps the hat snugly on your head even in high winds, and the ear flaps add extra warmth for working or playing outdoors.

Yarn:
Color A: 150 yd / 137m (green)
Color B: 50 yd / 46m (gray)
Color C: 50 yd / 49m (evergreen)

Needles specified:
3.5 mm (size 4 US) set 4 or 5 dpn
3.5 mm (size 4 US) 16” circular needle
or size to obtain gauge

Crochet hook: 3.25mm to 3.75mm
Tapestry needle for seaming