Indoor/Outdoor Ultrasonic Bark Stopper Training Obedience Device, Mountable and Handheld Up to 20 Feet Away An incredibly efficient solution to the common barking problem! Mount on a wall  easy to slide in and out of bracket! Handheld  take it with you wherever you go  indoors or outdoors! Barking triggers a high-pitched sonic pulse  audible only to dogs  to stop barking! Humane way to curb persistent barking in seconds!