Bottles and teats, and blockages.
Bottles, and teats all come in different shapes, sizes.
Different sized teats means that they're designed for potentially a better, or more comfortable fit in the babies mouth.
The different "numbered" teats generally mean that the "hole" at the top is a different size. This means that they can "flow" more milk during the feed.
Generally speaking the teats are either numbered from 0 to 3, or by babies months starting from "0+", progressing to "3 months+" and so on.
Some teats have a "valve" in them (for example Tommee Tippee teats have them) to help with the "return" of air back into the bottle as the babies drinks the milk out of the bottle.
At some point during feeding your baby, you may wonder why isn't the milk being drank, even if the baby is swallowing.
This may be due to the teat nozzle becoming blocked with the milk power.
This happens, and isn't a big deal.
Simply remove the bottle from the babies mouth. With the bottle upright verticle, with the teat pointing upwards, give the bottle a gentle firm squeeze.
This is to push some air that's at the top of the bottle out through the teat nozzle.
This will effectively squirt the blockage out.
It helps if you position the nozzle close to, but not touching your own lips.
You'll then feel a gentle jet of air on your lips when the blockage has been squirted out.
Alternatively, with the bottle removed from the baby, with clean hands / fingers, give the teat nozzle a quick squeeze, or roll the nozzle between your index finger and thumb. Depending on the size of the nozzle, you may even be able to see through the opening, down into the milk.
You only want to visually inspect the nozzle, ensuring no blockage, and then squeeze the bottle again so that a jet of air hits your lips, confirming that the nozzle is clear.
Now that its clear, continue feeding your baby.
As your baby grows, and gets stronger at sucking from the bottle, blocked nozzles become less if an issue, as the baby will be able to suck any blockages from undissolved milk powder straight in during their feed.
Information in this blog is from my own personal experience / observation and only for my own reference. If you find it useful, then great, buy it shouldn't be considered "gospel", and your own experience may and will differ as each baby / situation is different.