Before there was Gulf x TAG Heuer, there was Shell x TAG Heuer. Note the Shell logo at 9 o'clock on the crystal. I don't know the full origin story on these. It seems pretty rare, this one came to me from Japan. (@Snowy tells me they were available at Shell gas stations in Japan.) I'm guessing they might have been made for the Japanese GP, where Senna won all 3 of his WDCs. Also, Shell achieved 150 GP wins in 1991. Perhaps TAG & Shell wanted to celebrate that too. If others know more about the origin of this Shell x TAG collaboration, please chime in! As an aside, the Marlboro Red Formula 1 was the team watch of McLaren during the Honda era. Honda & Shell worked closely together on engine development. Even Senna wore a red F1 on occasion, as seen below at Suzuka '91 when he won his 3rd and final championship.