If you're taking a close look at Mark's lovely images, you'll likely notice that the Cal 400 models aren't that difficult to divine from the 733-powered options. The Cal 400 models have "5 Days" printed link on link the dial (for the 120-hour power reserve), and the date display sits somewhat lower on the dial than it does for the 733. Both of those elements can be seen in the image below, which is of a 43.5mm Cal 400-powered Aquis Date link Upcycle. link