Description: Rolex Daytona 16523 Pre-owned Rolex Daytona ref 16523 (1997). Before the in-house caliber 4130 was introduced in 2000, Rolex used a modified version of the Zenith El Primero self-winding movement to power its famous chronograph. Those watches were called the Rolex Zenith, and the ref. 16523, you see here is a two-tone version of that watch, which would later be replaced by the incoming ref. 116523 in 2000 with the caliber 4130. What’s also interesting