Product Features: Bark Free PRO Series features 25% greater dB output for increased effective range. Your dog's bark automatically triggers corrective ultrasonic bursts to help correct boredom or annoyance barking habits. Dual speakers. Selector switch for ultrasonic or audible settings. Sensitivity selector slide switch adjusts to your dog's barking pitch. Status led light (ON/Lower Power/OFF). Test button Wall mount or built-in standing design. Powered by adapter (included) or 4 "D" Batteries (not included). Twin dual piezo-ceramic transducers. 50 FT. Low-lead cable included. Up to 30 ft radius coverage area.