A TASER\xae and a vertical grip are combined to be attached to the stud post under the forend or the barrel of a conventional long arm. The communication between the acoustic and fluid air spaces is positioned so as to minimally interfere with the flow of air introduced, i. The data acquiring unit acquires detection data of the angular velocity sensor. The switch has a secondary resonant circuit receiving the applied signal from the primary circuit and couples a response signal back to the primary circuit.