PetSafe Electronic SmartKey for PetSafe Electronic SmartDoor COMPATIBLE PET DOOR: Key for all sizes of the PetSafe Electronic SmartDoor; not compatible with the SmartDoor Plus ADDITIONAL PETS: Can be used as a replacement or to add additional pets to your SmartDoor (up to 5 total) INDOOR/OUTDOOR ACCESS: Uses RFID technology to send a signal to the Electronic SmartDoor to unlock the flap and let your pet in or out; helps keep out unwelcome animals WATER RESISTANT: Key is designed to withstand submersion up to 5 ft. PACKAGE INCLUDES: 1 SmartKey and 1 Key battery (RFA-67) PRODUCT SUPPORT: PetSafe brand's US-based Customer Care experts will be glad to help; call, email or chat Monday through Saturday at 1-800-845-3274 EXPERIENCE: PetSafe brand has been an industry leading US manufacturer of pet behavior, containment and lifestyle products since 1991, helping millions of people and pets each year