dec·a·gon (dĕk′ə-gŏn′)
n. A polygon with ten sides and ten angles.

Lets use up some of the partial dk/worsted/aran yarns we all have in our stashes. MC is a bit more than 50g, CC is around 35g.

For the top decreases, use SSK or K2tog - whichever one has the MC on top for you.

Gauge is relative. Needle sizes are suggestions only. Use whatever needles gets you ~20 inches for 120 stitches in stockinette.

This hat is a bit of a longer slouchy hat (9 inches from top to brim). If you want it to be a tad shorter, for the horizontal stripes, knit 2 CC rows instead of 3 CC rows, this should reduce the length of the hat by about 1 inch without affecting the pattern too much.