I am waging a permanent war against the flies in our house. When you live in the country (and have animals!), flies really are a nusiance. I've been through loads of beaded and ribbon-type fly screens, which don't keep the flies out and do get stuck in the catflap/wrapped round your ankles. Also, if you've got little ones - they're not very safe. These insect door screens have been the only thing that has worked at keeping flies out of my house. They really do work, and the magnets really do snap shut once you've walked through. The dog hasn't found it a problem either. Do like I did and take some time to fix it up properly (maybe with a wooden baton along the top) then use the sticky things supplied to tape it down the sides of the door frame.