https://longshots.wiki/wiki/Fitting_a_Cat_Flap
This double-flap insulated cat flap is a great protection for all climates. It can be used in wood, uPVC and glass doors. It is crucial to have a door that seals well, especially in cold winter months. It prevents warm air from being sucked away and cold air from entering which can save money on energy costs. Wind Resistance By preventing cold air from entering your home and keeping warm air inside the home, a cat flap cover will keep it warmer. Most of the best options are insulated and have an electronic seal to prevent the draughts. The