The SL4 has been the gold standard for small utilitarian dive lights for decades. Owning a SL4 is owning a piece of scuba diving history. It is compact enough to slide comfortably into a BC pocket and has a bright center spot to light up dark spaces under any type of diving condition. Now, UK is introducing the updated and enhanced Mark 2 version of the SL4. For the first time, we are using a digital controller to take maximum advantage of all four C-size batteries. The SL4 Mark 2 boasts an eye-watering 600 lumens of brightness, while retaining all the great qualities that made it the most popular dive light in history.