It is a simple bottle that you press and it fills up with water on top. It is definitely not convenient to take it with you on the strap. You need a bag

Ideal for everything, from the beach to restaurants and walks. Better than open bowls, even upside down in a bag it doesn't lose a drop if not squeezed, worth having it everywhere.

I found it not so convenient after all due to its size, especially in combination with the lid. I also had an issue because, since it doesn't have a proper cap, it leaks water if you turn it sideways. It's good for its price, but I think bottles with a detachable container are more convenient.