Rolex, Cosmograph Daytona Zenith Movement, Ref. 16523

SPECIFICATIONS

Brand: Rolex
Model: Oyster Perpetual Cosmograph Daytona Zenith Movement
Reference Number: 16523
Movement: Automatic
Condition: Very good (some signs of wear due to age, can be eliminated with polishing)
Gender: Men’s
Time Period: 1991
Box: No
Papers: No 

THE CALIBER

Caliber: 4030
Jewels: 31

THE CASE

Case Material: Stainless steel
Case Diameter: 40 mm
Thickness: 12.5 mm
Waterproof: 100 ft./ 30 m./ 3 ATM
Bezel Material: Fixed 18K yellow gold engraved Cosmograph Tachymeter scale
Glass: Sapphire Crystal
Caseback: Solid
Dial: Sunburst champagne stick dial with black outer sub-dial rings 
Dial Numerals: 18K yellow gold applied baton and luminescent coating baton hour indices, minutes, and 1/5 seconds divisions scale around the outer rim

THE BRACELET/ STRAP

Bracelet Material: 18k yellow gold and stainless steel Oyster
Buckle: Crown folding 
Buckle Material: Stainless steel

THE FUNCTIONS

Center hour, minute and seconds hands, chronograph (center hand) accurate to within 1/8 of a second, column wheel, chronograph sub-dials counters 60-second at 9 o’clock, 30-minute at 3 o’clock and 12-hour at 6 o’clock, Tachymeter counter on the bezel, 54-hour power reserve.

FURTHER READING

Brushed and polished round-shaped case
18K yellow gold and luminescent baton hands, yellow gold applied stick center sweep seconds hand
Double quickset, stop-seconds for precise time setting
18K yellow gold and luminous insert baton-shaped hour/minute hands, yellow gold stick-shaped sub-dial hands, blackened arrow-shaped chronograph hand
18 yellow gold screw-down solid case back
18K yellow gold screw-down chronograph pushers at 2 (start/stop) and 4 o’clock (reset)
18K yellow gold triple-sealed waterproof screw-down crown with Rolex logo
Automatic 4030 Zenith movement 
The production period of this model was from 1989 to 2000. Afterward, it was replaced by the Rolex-own development Rolex 4130.
Self-winding movement, bi-directional winding, Breguet hairspring, Chronometer certificate (COSC), Stone lever escapement, Yoke winding system, Glucydur balance wheel with microstella screws, Kif shock protection for balance wheel and escape wheel
Adjusted to heat and five positions, monometallic balance, shock absorber
This mechanism oscillates at the frequency of 28,800 vph (4 Hz).
X serial number
Case, dial, and movement are signed.
Introduced in 1963 as a sports companion for professional race car drivers, the Daytona comes equipped with a Tachymeter bezel alongside the sub-dials to calculate speeds of up to 400 kilometers per hour. 
Incomplete (no box, no papers)