|Those components look really familiar.|
When I first started beekeeping I saw these really fancy screened bottom boards with a fancy drawer underneath for monitoring mites. They were expensive, they still are expensive. I am going to show you a quick easy way to make your own: cheaper, and a shitload more useful.
Take a screened bottom board, and point the ¾ inch entrance up. Place a solid bottom board underneath it with the 3/8 inch entrance up pointing in the opposite direction. Then simply take an entrance reducer and tack your mite monitoring sheet to it (in my case an old target).
Now you have a combination bottom board, a spare bottom board if you need it, and an entrance reducer all tucked into one hive. All made with what you probably had laying around anyway. Cheers.