2/4/6pcs Ultrasonic Pest Repeller, Smart Variable Frequency Insect Repellent, USB Powered Ultrasonic Pest Control, ABS Housing, Physical Pest Repelling, Silent Low Noise, Ultrasonic Smart Variable Frequency Insect Repellent, Physical Pest Repelling For Mosquitoes/Mice/Cockroaches, Suitable For Home, Kitchen, Office, Hotel, Warehouse, Effective Indoor Pest Elimination, Mosquito And Rodent Repelling. Better Effects Over A Period Of Time.