Convenience and freedom – No more planning around toilet breaks; give your dogs and cats the freedom and independence to come and go as they pleaseEasy 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 pets coming and goingUniversal Fitting – Works with brick walls, and wooden, metal or PVC/uPVC doors; includes simple cutting template and installation guide