Reference 16520 was a game changing chronograph released in 1988. Rolex moved from their long tradition using manual chronograph movements and introduced the caliber 4030, a modified Zenith-based movement. Additionally, the case was upgraded to 39mm diameter and it was the first Daytona to feature a sapphire crystal.

The reference 16520 bearing an “L” on the serial number, can be witnessed from the second half of 1988 until the first half of 1990, making the series a rare example of the early examples of Zenith Daytona. The first half of the production of the “L” series houses a 4-Liner dial with a 200 units per hour bezel insert. However, in the later production of the “L” series, the watch features the updated 5-Liner dial and fitted with a 400 units per hour bezel insert.

This lovely “L” series from 1990 features five lines of text at the 12 o’clock and serifs on the subsidiary dial with the 12-hour register featuring an inverted 6. The subsidiary dials have turned a charming yellowish light brown, which complement the black dial. Furthermore, it is also fitted with the upgraded 400 units per hour bezel insert, making the present example one of the last transitional examples from the late “L” series.