Description The PetSafe® Spray Refill cartridges are easy to replace with no mess. Simply remove the empty cartridge and replace with the new one. The citronella scent is harmless to your dog and is meant to act as a distraction to help stop nuisance barking. The Spray Refill cartridge is 100% recyclable and safe for you and your dog! Product features Compatible collars – The PetSafe® Spray Refill – Citronella is for use with the PetSafe® Spray Bark and Training collars; it is NOT compatible with the PetSafe® GentleSpray®, 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 cartridge100% recyclable – The disposable PetSafe® Spray Refill cartridges are 100% recyclable