Ratio Free Diver Helium-Safe Automatic 1068MD96-34VA-BLU 1000M Men's WatchThe Ratio II Helium-Safe Free Diver is built for deep-marine activities but looks plain enough for use by someone just sitting at the beachside pub. A Seiko workhorse finds way into it, strengthening it from the insides. It maintains an accuracy of -20 to 40 seconds when moderately regulated; finer regulations can bring it to within 10 seconds on either side.