Martin, I believe that is the "backlight mod" for the K1 - it illuminates the back of the LCD display so it can be read in the dark, or in very low ambient light levels. Drop the "l" from "Black" and you will have it right. 73, Don W3FPR On 6/15/2011 2:28 PM, Martin Staffa wrote: > Can I ask what is the black light mod? Thanks Martin >