Gauge isn’t super critical but if you knit tightly then do the ribbed neck in 4.5mm needles and the body in 5mm.

I used Pernilla 100% Peruvian Highland Wool (175m/50g) in colour 954 and Sandnes Garn “Tynn Silk Mohair”(57% mohair, 28% silk, 15% wool) (212m/25g) in colour 1022. Hold both together to knit the grey version (full neck). I used about 200m (1 and a quarter balls) of the Pernilla, and 200m (1 ball) of the mohair.

I also used Yarnsmiths Create DK to create a sample of a shorter neck to show it will work the same way. That’s the tan version shown in the pictures. I used less than 100g of that.