http://www.saberforum.com/index.php?topic=2346.0I am not one of US employees or anything but on the thread I posted above some of us have discovered ways. With the silver blades US provides filters. Some of the people on here have found the brand lee filters works great and for a reasonable price. You could use these on the other colors but you are going to lose brightness. Read the thread and see what you think.
Ultra might have another answer but for now here is an idea.
Hope it helps