You should Notice that commencing in 2005, Rolex began engraving the serial variety to the inner bezel (also known as the rehaut) under the crystal on the six o’clock position. Even though the crystals on the 160xx era of Datejust watches remain made from acrylic, the sloped "pie pan" design https://www.watchesworld.com/a-history-of-watch-reference-numbers/