I've asked this several times and no one has given me an answer, but today I managed to find out. I would say anyone care to guess but since some people have the new model already I'm guessing they already know. So on closer inspection the back has no lugs because the back does not come off the watch! The back is part of the case, this is how they've managed to get the helmet perfectly straight. The movement is accessed through the front of the watch, you take the bezel off and then remove the whole movement to get at it. Interestingly it was suggested that this will be the same for quartz models when they arrive, which means watches will have to go back to TAG for battery changes - unless you feel brave? I wonder if the fakers will still give it a regular screw down back?