Hi Rich Unlike disk write protects that need to block infrared, ultra violet is blocked by most anything. I like to use the white self sticking labels found at most stationary stores. These are easy to write on to indicate rev and other information. I've also taken scissors to the main labels for floppies and cut them into small enough strips to cover the windows. One can also get laser printer labels as well. It is true that over time the glue will dry and be hard to remove but googon (or similar) works well. Dwight