Petsafe collars that control a dog's bark are ideal because barking dogs disturb neighbors and can be a nuisance. The bark collar by Petsafe involves six levels of discipline while training the dog not to bark. It starts off at the lowest level and adjusts itself until the dog responds, but it will not prevent dogs from barking at intruders. If a dog barks for more than 30 seconds, the collar shuts itself off, and the dog's bark alerts owners of a problem. It is very comfortable for the dog to wear, and can be worn indoors or outdoors. This collar is safe for pets to wear, and it works.