You will need a cable needle.

Finished measurements:
Chest circumference: 24(26.5, 28.75, 31, 33)“ 61(67, 73, 79 ,84) cm
Finished length: 12.5(15, 17, 19.25, 20.5)” 32(38, 43, 49, 52) cm
Sleeve to armhole: 8(9.5, 11.5, 13, 15)“ 20(24, 29, 33, 38) cm

Yarn used:
James C. Brett Norska
Shade NK02 Lt Gray - on boy
Shade NK03 Lt. Blue - on girl
4(4, 5, 6, 6) balls