Dazer Ii Ultrasonic Aggressive Pet Dog Deterrent Dazzer The DAZER is a compact hand held ultrasonic dog deterrent designed for use by the general public in providing protection from aggressive, unfriendly dogs. Jog, walk, bicycle, work and enjoy the outdoors without fear of stray, unfriendly dogs. Helps stop the neighbors barking dog also. The DAZER emits a high frequency ultrasonic sound which dogs instinctively are deterred by and move away from.