SECURE YOUR SMARTDOOR: If you are installing your SmartDoor in a glass door, metal door or in a wall, use this adaptor to secure your pet door in place EASY TO INSTALL: Simply attach the adaptor to the interior and exterior of your SmartDoor frame during installation LARGE COMPATIBILITY: Large adaptor compatible with Large SmartDoor Connected Pet Door (ZPA19-17253, PPA00-17255, PPA19-17257) U.S.-BASED CUSTOMER CARE: Our pet product experts are here to help you and your pet and are available by phone, email or chat if you have any questions QUALITY PROMISE: PetSafe brand has been a trusted global leader in pet behavior, containment and lifestyle innovations since 1998 to help keep your pet healthy, safe and happy