This hat is a set with “Let’s Do Geometry Cowl” https://www.ravelry.com/patterns/library/lets-do-geometry-cowl

The hat works in one part, in rounds, down up. Model: slightly loose and elongated.

The pattern is given for 2 yarns: for yarn 125m/50g (yarn A) and 90m/50g (yarn B). Each yarn has 2 op-tions: with and without reverse.

Sizes: head circumference 48, 50, 52, 54, 56, 58, 60 cm.

Difficulty level: elementary; necessary skills – round knitting, knit and purl stitches, stitch increases, stitch decreases.

Needles:

Option А: circular needles 2.75 or 3 mm; 4.5 mm (40 cm long), 5 DPN 4.5 mm; 3.5 mm for sample;

Option В: circular needles 3.75 or 4 mm: 5,5 mm (40 cm long), 5 DPN 5.5 mm; 4.5 mm for sample;

Option А:
24 stitches x 35 rows = 10x10 cm in stockinette stitch with 3.5 mm needles after blocking.
Option В:
20 stitches x 30 rows = 10x10 cm in stockinette stitch with 4.5 mm needles after blocking.