What's interesting here is Omega has designed a new system of locking the case back to ensure that all the engravings on the rear of the watch stay oriented correctly – they call it a ceramic Naiad locking system. It is, of course, patented. (A quick look through the various patent databases turned up what looks like the relevant patent – basically it's for a locking system for a screw-down case back that allows you to orient decorative elements on the case back, such as engravings, in proper alignment without having to match a given case back to a given case; if you're curious you can take a look right here. The word "naiad" is Greek and refers to mythological water spirits.)