From the Pattern Booklet:

These directions are for children’s small size (4-6). Changes for medium size (8-10) and large size (12-14) are in parentheses.

MATERIALS WORSTED WEIGHT YARN (100 g balls/240 yds.) -- 3(4-5) balls (720(920-1200) yds.) 300(400-500) grams/11 (14-18) ounces 1 pair each straight knitting needles Nos. 3 and 6 (3.25 mm and 4.25 mm) OR ANY SIZE NEEDLES THAT WILL GIVE THE SPECIFIED STITCH GAUGE 1 set dp needles No. 3 (3.25 mm) 1 cable stitch needle GAUGE: 6 sts = 1 inch 8 rows = 1 inch