Double glazing can be fitted with dog and cat flaps to allow your pets to come and leave whenever they want. They also help in keeping an eye on your pet whilst you are away from home. You can install a cat flap in an existing uPVC or double glazing https://double-glazing-cat-flap01053.ampblogs.com/installing-a-cat-flap-in-a-upvc-door-cost-67582749