Budgie Mittens are knit in the round from the bottom up, and include a shaped thumb gusset. Sizing is changed by adjusting the gauge and using the appropriate charts.
Sizes Small and Medium are worked with a gauge of 9 stitches/inch. Sizes Large and Extra Large are worked with a gauge of 8 stitches/inch.
Sizes Small and Large share the same hand and cuff charts, and sizes Medium and Extra Large share other hand and cuff charts. Thumb charts are the same for all sizes.