This is a super warm hat when knit with Roving Yarn!
It’s my go to hat for super cold days. It stretches a bit and becomes oh so comfy!

Bernat Roving is perfect for this hat. It is a thin 5 weight yarn.

Some roving yarn I have noticed is a bit thinner so you may have to adjust either your stitch amount or needle size to meet the gauge.
Testers have used a variety of yarns that you can see below.
A thin 5 weight yarn works best in my opinion.