Our audio jammer protects room conversations where sensitive information information may be exchanged by generating a random masking sound which desesitizes any microphone that is near. This jammer is effective against any microphone based eavesdropping device including tape recorders, RF transmitters, hard wired microphones and shotgun microphones. Specifications Protects up to 150 sq ft of space End mounted control Includes 9V Battery Illustrated instructions Size 4 1/2 x 2 1/2 x 1 1/2