The PetSafe spray bark collar gently and immediately conditions your dog to stop barking using a harmless burst of spray. The collar uses a microphone to pick up your dog’s bark, which triggers a harmless burst of spray. The spray distracts your dog from whatever he’s barking at, letting you redirect your dog’s attention. This spray collar is safe for all dogs, including puppies. Soft spray stops barking. 25-30 sprays per refill. For dogs of any size. Sound sensor detects bark. Water-resistant collar uses a 6V alkaline battery (included). To refill the collar, make sure the unit is turned off. Hold the refill spray can upright and firmly press the nozzle down into the refill port. Hold for 15 seconds or until the unit is full, then remove the can. If spray leaks out, you may need to press harder to complete the seal.