This is an anti-bark collar. It vibrates when your dog barks, startling them and stopping the unwanted barking. There is no electric shock. You can adjust the vibration strength and also make it emit a sound along with the vibration. The effectiveness varies depending on the dog, so please try it out. I used it on a small dog, so it can be used for dogs with a neck size of around 25 cm or less. I'm selling it at a low price because it doesn't come with a box or instructions. - Type: Anti-bark - Color: Black - Features: Remote control operation - Power: Rechargeable - Band Material: Nylon Thank you for looking.