This is the UK Underwater Kinetics SL4 eLED MK2 600 Lumens Scuba Diving Features: Gold Standard for Small Utilitarian Dive Lights for Decades Owning a SL4 is Owning a Piece of Scuba Diving History Compact Enough to Slide Comfortably into BC Pocket Bright Center Spot: Lights Up Dark Spaces Under Any Type of Diving Condition Updated and Enhanced Mark 2 Version of SL4 Light Digital Controller: Maximizes Advantage of All 4 C-Size Batteries (batteries not included) Eye-Watering 600 Lumens of Brightness Powered by: 4 C Alkaline / LR14 Disposable (batteries not included) Burn Time: 6-Hours he 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, UK is 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. "