What is a small air pump that fits on a plastic bottle for???

Question

What is a small air pump that fits on a plastic bottle for???
That small pump can be bought at a grocery store.
Urgent, It's my homework!!!

10points for best answer.

Answer 1

It sucks the air out of the bottle so the contents stay fesh'er'.

I have one, works great.

Hope we're talking about the same pump.

Good luck with that homework, I'm so glad to be done with school and in a position to torture others as a teacher.