The PetSafe® RFA-67 6V Replacement Battery 2-Pack are replacement batteries that work with the PetSafe® bark collar, in-ground and wireless fence receiver collar systems. These batteries are waterproof and last 1-3 months, depending on use. PetSafe® brand is here to help you and your pet live happy together™. Features Compatible collars: Wireless Pet Containment System Receiver Collar Stay & Play® Wireless Fence Replaceable Battery Receiver Collar Deluxe UltraLight™ Receiver Collar Basic Bark Control Collar Compatible fences: Wireless Pet Containment System™ Stay & Play® Wireless Fence with Replaceable Battery Collar Basic In-Ground Fence™ System In-Ground Fence™