What kind of Fly Repellant do you use?

Flies can become a nuisance in the summers although it is a time to get outdoors and have fun and even if you don’t go out yourself, you can open the doors to let the breeze in. However the flies will find their way inside the moment anybody opens the door. It is better to use some kind of fly repellent to keep the flies out of your way as much as you can and for those that are still stubborn...