It is recommended to hire an professional to install a cat-flap inside your home. DIY projects typically result in poorly fitted pet flaps which allow drafts and cause higher energy bills. SheffLOCK can be installed as the cat flap into all kinds of doors, including wood, uPVC, composite and glass https://window-with-cat-flap65908.answerblogs.com/30981127/using-a-cat-flap-in-bifold-doors