Size:

[2 generation nipple] s number (0-3 months)

[2nd generation nipple] M (3-6 months)

[2nd generation nipple] L (6 months +)

[2 generation nipple] Y (12 months +)

[3 generation nipple] s number (1 month +)

[3 generation nipple] M (3 months +)

[3 generation nipple] L (6 months +)

[3 generation nipple] LL No. (9 months +)

[3 generation nipple] 3L (15 months +)