Do power strips/bars just pass through the electricity, or do they also need to be dual-voltage rated?

I'd love to pack a little travel-sized power strip so I don't need multiple adapters - plus I might not always have easy access to multiple power outlets.

Belkin, for example, has a travel-sized one but if I used it with a plug adapter for New Zealand, can I plug in any of my devices as long as THEY are dual-voltage rated?