The Quadblaster QB4 Is A BEST SELLING Ultrasonic Bird Deterrent Device That Gets Rid Of Bird Infestations With A Silent To Humans Audio Attack. 4 Built-In Speakers Emit High Frequency Sounds. The Sounds Are Designed To Confuse, Disorient And Intimidate Pest Birds To Quickly Scare Them Away From The Effective Area. Birds Will Not Linger While Exposed To This Sound! Most Trusted Ultrasonic Solution-This Industry Favorite Is Used Worldwide, Protecting Facilities From Damage And Liability. Use Indoors Or In Semi-Enclosed Spaces. Covers Up To 6,500 Square Feet.