https://securityholes.science/....wiki/Cat_Flap_Double
A wall-to-wall cat flap is a great method to let your pets move around whenever they like. But, you should be careful not to place it too high in the wall. This could result in energy loss and burglars to break into your home. A gap in a cavity can also be a problem for future owners if you intend to sell your home. Glass cat doors are a much safer option. Easy to install A wall-to-wall cat flap lets your cat to come or go as it pleases. It's simple to set up, and there are several models to choose from. Some even allow you to