Using your PetSafe Electronic SmartKey Collar Key is easy. First, attach the SmartKey™ to your pet's collar ID tag. Make sure it's securely fastened. Then, if you're adding a new pet to your SmartDoor™, follow the door's instructions to pair the SmartKey™ with the door. When your pet approaches the door, the SmartKey™ will automatically send a signal to lock or unlock the flap. For maintenance, keep an eye on the battery. The included RFA - 67 battery usually lasts 3 - 6 months. When it starts to run low, replace it with a new RFA - 67 battery. Remember, this SmartKey™ is only compatible with all sizes of the PetSafe® Electronic SmartDoor™ and not the SmartDoor™ Plus. Keep the SmartKey™ clean and dry to ensure it works properly. If you have any issues, contact PetSafe® customer support for assistance.