The first series of adaptors that were introduced to the market did not have a built-in overload protection. Therefore, the series was withdrawn and new secured adapters came on the market. Below is a picture of the first series (the adapter to the right) and the new secured series (adapter to the left). Read more about security in the instructions that you find on the site, or see the Youtube clip (here) that shows that the adapter is protected against short circuits even in extreme cases.