Due to a regulation set by Google, it is impossible to block a device.
However, in order to overcome that obstacle, we detect a device by its ID.
This ID is a special value generated by our system that is unique for each specific device (be it a mobile phone, a desktop/laptop or even a tablet).
This ID can not be altered under any circumstances and remains constant.
Based on that device ID we can detect all new IPs that come from the specific device.
If we detect that the device was used for fraudulent activity, our system tags it as fraudulent and now, everytime this device will be used for fraudulent activity against your ads, the new IP it uses will be blocked after the first click, regardless of your threshold.