The outer shell of Beosound Explore features Type II anodised aluminium. Type II anodising is a process where the aluminium is put in a sulfuric bath, building up the aluminium oxide on the surface.
This makes the surface much more scratch and wear resistant than aluminium treated in traditional ways, meaning Beosound Explore will look newer for longer and not be damaged as easily, should you, for example, put the speaker in your bag along with your keys.
Note that this relates to extra protection against surface wear and scratch resistance but does not guarantee that the speaker cannot be scratched or dented.