The PetSafe® Spray Refill cartridges are easy to replace with no mess. Simply remove the empty cartridge and replace with the new one. The unscented refill cartridges are great for sensitive dogs – a small spray to the snout without added scented oils or fragrances. The PetSafe® Spray Refill cartridge is 100% recyclable and safe for you and your dog! Key Features: •Compatible Collars – The Spray Refill - unscented is for use with the PetSafe® Spray Bark and Training collars; it is NOT compatible with the Elite Big Dog and Little Dog Spray Bark Collars or Elite Big Dog and Little Dog Spray Trainers. •Easy-to-Replace – The refill cartridges are easy to replace; simply remove the empty cartridge and replace with the new refill cartridge. •100% Recyclable – The disposable Spray Refill cartridges are 100% recyclable. Features: •Compatible with PetSafe® spray Bark Control Collar (PBC17-16369) or spray Remote Trainer (PDT17-16396). System Includes: 3 unscented Refill Cartridges. Each cartriges delivers between 35-40 sprays.