Keep bark training on track with PetSafe Citronella Spray Refill cartridges for dogs. These easy, no-mess refills slide in and out quickly—just remove the empty cartridge and replace it with a new one. The gentle citronella scent is harmless and designed to distract your dog to help reduce nuisance barking. Each disposable cartridge is 100% recyclable and compatible with PetSafe Spray Bark and Training collars (not compatible with Elite Big Dog/Little Dog Spray Bark Collars or Elite Big Dog/Little Dog Spray Trainers). Ideal for dog training and positive reinforcement routines using a bark control spray collar.