Calibre 3155 is a self-winding mechanical movement entirely developed and manufactured by Rolex. It features a day and date calendar disc mechanism. Like all Rolex Perpetual movements, the 3155 is a certified Swiss chronometer, a designation reserved for high-precision watches that have successfully passed the Swiss Official Chronometer Testing Institute (COSC) tests. Its architecture, in common with all Oyster watch movements, makes it singularly reliable.
Caliber 3155 stands at 6.00mm tall and features 31 jewels. It was introduced in 1988.