I have been seeing old posts indicating they were buying drone frames.
Why would you want drone frames in a hive. I thought you wanted to minimize the quantity of drones. Would these be for raising queens or am I missing the point altogether?
Varroa mites prefer to lay eggs in drone cells. A drone frame is supposed to draw the mites to lay in with the drone larva. The frame is removed and frozen after the cells are capped, thereby killing the unhatched varroa mites.