It comes in the following sizes: size 1 for babies aged approx. 0 ? 3 months and size 2 for children aged approx. 3 ? 24 months. Teats with different feed-hole sizes are available depending on what you are feeding ? with feed-hole sizes for tea (S), milk (M) and cereals (XL).These feeding teats all have an anti-colic valve, which equalises the pressure in the bottle during feeding and minimises the amount of unwanted air your baby swallows.