The Rolex Cosmograph Daytona reference 16520 is a prized collector’s item among Rolex Daytona enthusiasts. In addition to offering a handsome all stainless steel finish, this ref. 16520 also boasts a steel Tachymeter bezel, a white dial topped with Tritium luminous plots, and a self-winding Caliber 4030 movement. Also known by collectors in-the-know as the Zenith “El Primero” movement, the Cal. 4030 was produced by Zenith and then modified by Rolex to meet their strict specifications. The ref. 16520 was the last stainless steel Daytona to run on the Caliber 4030 before being replaced by a movement developed and produced entirely in-house by Rolex. Today, these “Zenith Daytona” watches are highly collectable and represent an important time in Rolex’s company history. If you’re in the market for a striking piece of horology, the pre-owned Rolex Daytona 16520 is the watch to purchase.