Description: Rolex Daytona 16523 Pre-owned Rolex Daytona ref 16523 (1997 – 1998) hails from the Daytona’s second generation, the series before Rolex started equipping its watches with in-house movements and relied instead on the outsourced Zenith El Primero movement. Zenith supplied the base for the caliber 4030, and Rolex then modified it in-house to remove the date display and bring the movement up to its strict standards. Watches powered by the unique engine