The Premier Pet™ Spray Refill Cartridges are safe and easy to use with no mess! Simply slide the button, remove the empty cartridge and replace with a new cartridge – available unscented or citronella scent. The Premier Pet™ Spray Refill is 100% recyclable and safe for you and your dog. The Spray Refill Cartridges work with the Premier Pet™ Spray Bark Collar.