Olive's Ribbed Balaclava

Olive’s Ribbed Balaclava is worked from the top down in an elastic rib pattern and fits snugly without being too tight around the face. It is worked with 2 strands of Merino held together throughout, and both flat and in the round.
You start working the crown in the round before working back and forth to create the face opening. Work is later joined under the chin and continued in the round before it is once again divided, and front and back neck are finished separately back and forth. Finally, stitches are picked up around the face opening and the face band finished in rib.
Please note that whenever only one number is given in the instructions, this number refers to all sizes.

Sizes: 6-9 months (9-12 months) // 1-2 years (3-7 years, 8 years to adult) to fit head circumference: 39-43 (43-46) // 46-49 (49-53, 53-57) cm [15¼-17 (17-18) // 18-19¼ (19¼-20¾, 20¾-22½)]”
Yarn: 2 strands of Knitting for Olive Merino (250 m [273 yd] / 50 g [1.8 oz]), fingering-weight yarn, 2 (2) // 2 (2, 3) balls. Sample is in Merino in Soft Blue colorway
Needles: 3.5 mm / US4 circular needle in 80 cm cable length (for Magic Loop) or double-pointed needles, or in size to obtain gauge
Gauge (after blocking): 26 sts and 37 rows = 10 cm [4”] in 2x2 rib pattern with 3.5 mm / US4 needles
Notions: Stitch markers, stitch holders, waste yarn, tapestry needle