Dev Patel wears a Casio Databank DBC-32

Chappie is Neill Blomkamp's third science fiction film set in Johannesburg, after District 9 and Elysium. Dev Patel plays Deon Wilson, an engineer at the weapons company Tetravaal who cracks artificial consciousness in his spare time and loads it into a decommissioned police robot. The robot, played by Sharlto Copley, gets adopted by the South African rap-rave duo Die Antwoord, more or less playing themselves, and Hugh Jackman turns up as a rival engineer with a mullet and a much bigger machine.

On Deon's wrist, while he works, is a Casio Databank: a calculator watch. You can see it clearly in the film, a black resin square with a tiny keypad and an LCD, the kind Casio has sold since the 1980s to engineers and students who wanted a calculator and a few phone numbers on their arm. The watch-spotting sites that catalog film props call it the DBC-32, which matches what is on screen and still sells for about thirty dollars. It is, by some distance, the cheapest piece of technology in the film.