You will need a cable needle.

You will also need a size US 5 (3.75 mm) circular needle no longer than 16” (40 cm).

Yarn is held double throughout.

Finished measurements:
Chest circumference: 32( 35.75, 39.75, 43.5, 47.25, 51, 56, 59.75, 63.5)“ 81.5( 91, 101, 110.5, 120, 129.5, 142.5, 152, 161.5) cm
Finished length:
Sleeve seam:

Yarn used:
Rowan Kidsilk Haze
Shade 590 Pearl - 9(9, 10, 12, 13, 14, 15, 16, 17) balls