This stereo jack plug with programmable button by Delock will be plugged into the stereo jack port and is suitable for smart phones and tablets with Android OS. It just needs an application (APP) to assign various functions to the Smart Key, e.g. take a photo, start video recording, switch on torch, SOS and many more. To improve the convenience it is also possible to use the defined functions while the display is locked. In addition, the Smart Key serves as a dust cover on the stereo jack port.