You will need a cable needle.
If you are also making the cowl, you will need a size US 7 (4.5 mm) and size US 8 (5.0 mm) circular needle no longer than 24” long.

The cowl is made and worn separately from the sweater, but the total required quantity is for the sweater and cowl together. If you want to make the cowl by itself, you will need 3 balls of yarn. Conversely, if you do not want to make the cowl, you should deduct approximately 3 balls from the total requirements.

Finished measurements:
Back width: 24.5(28, 32)“ 77(80, 83) cm
Total length: 30.5(31.5, 32.5)” 62(71.5, 83) cm
Sleeve length to armhole: 17.5” for all sizes 44(45, 45) cm

Yarn used (for entire project):
Rowan Kid Classic
Color 866 Bitter Sweet - 14(16, 19) balls