Petsafe, Citronella, Spray Refill Cartridge, Easy To Replace With No Mess, Simply Remove The Empty Cartridge & Replace With The New One, Citronella Scent Is Harmless To Your Dog & Is Meant To Act As A Distraction To Help Stop Nuisance Barking, 100% Recyclable, Safe For You & Your Dog, To Be Used With Spray Trainer Collars TV #261-020 & TV #261-021.