SainSmart Digital Capacitive Switch Touch Sensor for Arduino, TTP223B Jog type : the initial state is low , high touch , do not touch is low ( similar touch of a button feature ) Module can be installed in such as surface plastic, glass of non-metallic materials In addition to the thin paper ( non-metallic ) covering the surface of the module , as long as the correct location of the touch , you can make hidden in the walls, desktops and other parts of buttons