Bulky adult version.
Gauge 14sts / 4 in with US9.

Knit reds together with US9, brown with US10.5 to even gauge. Didn’t look at pattern, just used the same construction I remembered from the kid-sized mittens and did a little math and a little ripping / reknitting when things didn’t fit right.

CO 20 sts.
9 stripes of 2-row 2x2 ribbing of each color.
Increased 4 sts in first row of body (stockinette).
Knit 5 rows in round before decreasing for thumb.
Decreased to 14 sts: 2/each RS row on ends.
4 rows no change in st count.
Increased to 26 sts: 2/each RS row at ends.
4 rows in round.
Started 2-row stripes. Decreased to 24 sts.
K4, K2tog. Repeat around.
Knit around.
K3, K2tog. Repeat.
Knit around.
Continue as est, then pull yarn through at end.

Thumb: Knit 2-row stripes of alternating colors.
PU 30 sts
K8, K2tog. Repeat.
Knit around.
Knit 7, K2tog. Repeat.
Knit around.
Knit 6, K2tog. Repeat.
Knit around.
Decrease with K2 or K3 tog around to get to 9 sts for thumb.
Knit around each row until long enough for thumb.
Pull Yarn through.