Abstract: A security device, intended for use as a temporary or permanent vehicle security device, having an intrusion detection device in the form of a pair of electrical contacts supported on a shock amplifying, rigid base and responsive to percussive-type forces for generating a detection signal. At least one of the electrical contacts is supported on a relatively stiff cantilevered arm which will not respond to small movements and vibrations, to thereby avoid generating frequent false alarms. Any contact closure signal from the electrical contacts is processed by a detection circuit which counts multiple contact closures and/or measures total closure time, thus ignoring signals generated from small forces or vibrations, thereby preventing against the source of most false alarms when generating a detection signal.