Dog Silencer & Dog Trainer - This dog behavior correction device helps with dog training & behavior aids. It has Sound and 2 Ultrasonic modes with a frequency of 22-25 kHz thats hard for humans to hear. Its like an electronic dog whistle. Effective - Dog barking control devices effectively retrain barking. They're safe for dogs 5-120 lbs, from 6 months to 8 years old. Use this bark control device to also stop your dog from chewing, digging, and other destructive behaviors. Safe & Long Lasting - Dog barking deterrent works up to 16 ft and shuts off after 10 sec as a safety feature. It has a 450 mAh battery and works up to 14 days without charging. Easy to Carry and Use Indoor and Outdoor - The ergonomic design fits nicely in your hand, while a carabiner lets you take this ultrasonic dog bark deterrent anywhere.