I've got a clone diffusion filter and clone lens covers on order. Since Surefire discontinued most of their filters, many of them have become almost impossible to find.
I wanted to get a cover for the lens of my KT-1 turbo-head (good luck finding a discontinued FM27), and wanted to find a lens cover for my U2, but was willing to settle for the clone of the diffusion filter (and good luck finding a discontinued FM24). Both of those that I ordered are made by a company called "Element", and I believe they were made to cater to the airsoft crowd.