There's a few places that are really great to put a warning on a device. As a manufacturer, you can put a warning on the box of a bit of technology, just so long as that warning isn't going to tell the user about a possible blast into the ear. If there is going to be a blast into the ear of the user, the user would probably be better off having the warning about the blast be on the device itself. Sometimes there's another place for a warning, and that's deep within the device, under all the plastic, under all the metal. This is sometimes also known as Silicon Art.