Train your dog to stop barking. Ultrasonic and audible mode selections. Audible: creats harsh buzz to stop barking. High and low modes ( high for big dogs￡? low for small dogs) Dogs quickly learn that their barking causes this irritating sound and stop barking to stop the noise. Ultrasonic: works by sending out an ultrasonic signal that only dogs can hear when activated by the barking. The ultrasonic sound is 100% harmless. Adjustable stretch collar to fit different sizes. Trigger accurately by bark vibration (can not activate by other dogs barking)user manual                                    Features            100% Humaneand safe:harmless to your dog￡?no electric shock.Red light working indicatorON / OFF buttonsHigh / Low volume buttonsPowered by 2 AG10 cell batteries (included)For most dogs￡? it needs 7 to 14 days to take effect; for few dogs￡? it needs 4 to 6 weeks to take effect; for very few dogs￡?it needs longer time to take effect.                                                            Specifications            Collar length    11.8"    <br>Demension    2.36 x 2.36 x 0.39in/6 x 6 x 1cm(L x W x H)    <br>Weight    3.15oz/89.3g    <br>                                                            Package Includes            1 X bark stop1 X user manual2 X cell batteries