For this pattern I used Drops Eskimo in double strands.

To make the hat and pompom you will need 4 balls of Drops Eskimo

You will need a 20mm hook or a minimum of 19mm

If you would like a smaller/larger size, decrease/increase the number of chains in the starting chain (keeping an even number).

if your preference is a slouchy hat, keep working in the pattern until the desired length is achieved, then work decrease row as normal.