DNR Tech. ET Pest Control Special Buy 3 get 1 FREE! .1 in the Quantity Box. = 4 ET's Direct Pest Targeting High Range Insects/Bats and Low Range Rodents. Switch up the Ultrasonic Sounds with the click of a switch. Fixed Pitch = Two High Impact Holding Tones out of each speaker Tageting either High or Low Range. Variable Pitch = High Impact Siren effect cover all Ranges High and Low. "Repelling All" High Impact Electromagnetic for Deep Inner Wall Repelling. No Adjustment as it starts the minute you plug-in.