Smokey, here is a vid of the robbing screens that I purchased a few years back, I still use them every year.
When you put the screens on at night when the bees are all inside the hive... the next morning they have to learn how to get back out and back in, but it only takes a couple days for them to learn that. But the robbers don't know how to get past the robbing screen from the outside. So, the bees from the hive with the screen learn how to climb up to the top of the screen and fly out, turn around and reorient, then fly away to forage, then come back and re-enter the hive thru the top of the screen. The robbers have not learned this tactic so they fly away.
I would not go thru a summer without robbing screens, robbers can decimate your entire hive within a hour while you are at work. So sad to come home and find thousands of dead bees in front of your hive. YouTube has many vids on DIY robbing screens.