A normal 16520 Zenith Daytona is highly collectable in today's market. This is not what we have here. This is what is known as a Patrizzi dial Zenith Daytona due to the sub-register outer rings ability to turn from their original silver color to a brown color. This change is only seen with 16520s between S and early T serials (1993-1996). This example fall squarely in this range with a W-serial (1994). The exposure to UV light causes this effect and it is highly desirable by collectors. The watch here has subsidiary outer tracks that have not turned quite as dark as other examples, but that leaves the next owner a great opportunity to witness this effect over time.