Lee has one also. I think I got a free one from their website, and later they were kind enough to send me another after misplacing it. So I did receive two, I just don't remember how I initiated the acquisition.

One of the few optical things my wife was impressed with was me randomly choosing a red and blue pair of filter sheets from the Lee swatchbook and taping them to her glasses so she could watch some 3D TV movie with prescription 3-D glasses. I had no idea whether L/R made a difference.

Now, how about colored flash filtering for b/w, the opposite of filtering the lens...does that work with macro subjecture (I know it can't simulate clouds)?