Gauge 18,5 sts x 24 rnds in circular knitting.

With 4,5 mm needles CO 28 sts, joint to knit in round (magic-loop method) and work 7 rnds in 2x2 ribbing.
Change to 5,0 mm needles.
Rnds 1-7: knit all sts.
Rnd 8: k2, pm, M1L, k1, M1R, pm, knit to the end of the round.
Rnds 9-10: knit all sts.
Rnd 11: k2, sl m, M1L, knit to next marker, M1R, sl m, knit to end.
Rnds 12-13: knit all sts.
Repeat rnds 11-13 2 times more: 36 sts overall, 9 thumb sts.
Next rnd: K2, slip thumb sts on stitch holder, CO 1 sts using the backward loop method, knit to the end.
Continue to work in stockinette stitch for 5 rnds.
Change to 4,5 mm needles and work in 2x2 ribbing for 17 rnds.
BO with Elisabeth Zimmernan’s sewn binding off.
With 5,0 mm needles pick up 9 thumb sts on holder plus 3 sts more across the opening (12 sts). Knit 8 rnds in stockinette stitch and and BO.