https://www.openlearning.com/u..../bryantpuggaard-smjj
If you wish to let your pet to go and come at their own pace, without having to open the door, you can install a cat flap. It is recommended to hire a professional to install the cat flap. They can take care of fitting different kinds of cat flaps onto different doors and walls. Installation With a cat flap your pet is able to enter and out of the house at will without you having to open the door. The variety of pet flaps available on market is extensive, ranging from microchip-proof and bite-proof