Jon Hamm wears a Jaeger-LeCoultre Reverso

In one scene Don Draper is out of his usual suit, in an open plaid shirt over a white undershirt, a telephone pressed to his ear and his jaw set hard. A dark watch sits low on his wrist. Jon Hamm plays Draper, a Sterling Cooper ad man living under a stolen name: he took a dead officer's identity in Korea and built a Madison Avenue life on it, and across seven seasons he works to keep the man he used to be, Dick Whitman, out of view.

The watch that came to define him is a Jaeger-LeCoultre Reverso Classic. It is a rectangular Art Deco design from 1931, made for British officers playing polo in India who kept breaking their crystals: the case slides on its track and flips face down, so a panel of plain steel takes the knocks instead of the glass. Jaeger-LeCoultre was on Draper's wrist through the front half of the series, and Mad Men eventually ran a collaboration with the brand so viewers could buy the watch themselves. Hamm needed convincing. By the account of Gay Perello, the show's prop master, the first watch they tried was a JLC Memovox the producers never warmed to, and when they offered the Reverso he pushed back: "I'm kind of a round watch face guy." The flip case changed his mind.

The case flips for a practical reason, and on Draper it does a second job. One side shows the time; the other turns the dial away behind a featureless metal back. By GQ's account Draper buys the Reverso when he makes partner, and the show uses that hidden face: his wife Betty has the piece engraved, setting his initials on the blank steel back, the side that never shows the time.