What type of stitch is this?

Hello!

I found this cool hat at the store and now I want to try knitting one for my husband. I think it’s some kind of rib stitch, but I can’t quite figure it out.

I’ve tried K1 P2, but that’s not right. I’m wondering if the pattern has to do with the manufacturer using different sized needles for each rib (small for the knit and large for the purl).

Any suggestions? Thanks!

It’s a brioche st orFisherman’s rib. You get the effect by knitting 1 in the stitch below, or doing a slip/yo and knitting those together on the next row. Same thing, just done differently.