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 TrainersEasy 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