The Staywell® Original 2-Way Pet Door offers your dogs and cats the freedom and independence to come and go as they please. The 2-way pet door provides pet parents the option of snapping on a closing panel from the inside for convenient control over their pet’s coming and going. With the provided cutting template and easy installation guide, fitting this pet door is a simple DIY project. An optional tunnel extension made for thicker doors and walls is included with the medium and large size pet doors and is sold separately for the small size pet door. This pet door works with brick walls, and wooden, metal or PVC/uPVC doors. Trust PetSafe® to help to keep your pet healthy, safe and happy. Features Convenience and freedom - No more planning around toilet breaks; give your dogs and cats the freedom and independence to come and go as they please Easy installation - Simple DIY project to install; optional tunnel extension made for thicker doors and walls (sold separately for the small size pet door) Closing panel - The 2-way pet door provides pet parents the option of snapping on a closing panel from the inside for convenient control over their pet’s coming and going Universal Fitting - Works with brick walls, and wooden, metal or PVC/uPVC doors; includes simple cutting template and installation guide