The Rolex Cosmograph Daytona 116520 is the steel-bezel generation of Rolex's flagship chronograph, and this 2000 example is from the very first year of production. The 116520 succeeded the 16520 in 2000 and was the first Daytona ever to be powered by an in-house Rolex chronograph — the Caliber 4130 — ending the brand's reliance on the modified Zenith El Primero movement that had powered Daytonas for the prior twelve years. The 40mm Oystersteel case carries the engraved tachymeter on the polished steel bezel that distinguishes the 116520 from the later 116500LN ceramic-bezel generation, with screw-down Triplock crown and screw-down chronograph pushers preserving 100 meters of water resistance. The black dial features applied luminous hour markers, three contrasting white subdials at 3, 6, and 9 — the 30-minute counter at 3, small seconds at 6, 12-hour counter at 9 — and the red "Daytona" script above the running seconds. Caliber 4130 is a column-wheel, vertical-clutch chronograph composed of 290 parts and 44 jewels, beating at 28,800 vibrations per hour with a 72-hour power reserve, and Superlative Chronometer certified. Pre-owned, 2000 first-year example of the in-house Daytona era.