In the past, many bee keepers have taken a frame out of the deep (brood) box on the outside of the brood nest, maybe number 3 or number 8 and replaced it with a medium frame. The girls of course fill in the extra empty space below the medium frame with burr comb. This comb is almost always filled in with drone sized cells. So now you have a small section of extra, free floating drone comb on the bottom of this medium frame to check for mites. You went in with a capping scratcher and if there were mites in the sealed brood, you just cut that section of drone comb off the bottom of the frame and let them build it out again, thus removing all the mites in that whole section of comb.
Now they are saying that's not enough. The thinking now is you need to remove an entire frame's worth of drone comb from each brood box, so that's two frames if you run a two deep hive.
The manufacturers are responding to this and putting out both plastic and wax drone sized comb and foundation. The plastic frames even come in different colors, like dark green, so you don't have to remember which frame it is in each hive, just go to the green frame, pull it, freeze it and you're done!
This is of course only one part of an ipm system. Hope this helps, good luck! :D
