Hi everybody. I've never owned a G-shock before, so this will be my first purchase. I dive quite often, including shore dives, so I wanted a watch with Tide and Moon functions. I originally looked at a Gulfman (difficult to find) and a Frogman (difficult to find and too expensive) and finally settled on a G-7900 Rescue. I like the 7900-2 for the blue and yellow color scheme (my dive gear is blue and yellow, so why not my watch as well), but I've noticed listings for a 7900-2D and a 7900-2E. Looking at pictures of them, I cannot see a difference. Does anyone know what the difference in the last letter designation is? Thanks!