How to choose branded tech gifts that people will actually keep?

Some time ago, I visited a local business conference at which companies used to give some promo items like pens, notebooks, or tote bags. Most of the people put them in their bag after the conference without even thinking about it.

The one thing that I saw used right from the beginning was a portable charger. Some participants had low phone batteries, so it turned out to be one of the most helpful things at the conference. I understood that something more practical could leave a better impression on customers than traditional giveaways.

Now I'm working on a new idea for corporate giveaways, and my choice will be a portable charger instead of something else. Hope this make sense?