Pattern also includes instructions to knit matching booties (separate Ravelry entry here).

Sizes: to fit chest / actual measurements
0-6 mo (chest size 16”/41cm) / (17.75”/45cm)
6-12 mo (chest size 18”/46cm) / (20”/51cm)
1-2 yrs (chest size 20”/51cm) / (21.75”/55cm)
2-3 yrs (chest size 22”/56cm) / (23.75”/60cm)
4-5 yrs (chest size 24”/61cm) / (25.5”/65cm)
6-7 yrs (chest size 26”/66cm) / (28”/71cm)

Yarn Requirements: DK weight, 50g balls
2 (3, 3, 4, 5, 6) balls