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https://writeablog.net/polandd....ance7/installing-a-u
A through wall cat flap is a great way to allow your pets to move around as they please. Be careful not to install it too high into the wall. This could lead to energy loss and the possibility of burglars gaining access to your home. A gap in a cavity could be a problem for future owners should you decide to sell your house. Glass cat doors are a safer alternative. Easy to install A wall-to-wall cat flap