The Rolex Cosmograph Daytona 116520 represents a defining chapter in modern chronograph history. Introduced in 2000 and produced until 2016, this reference marked the first Daytona to be powered by Rolex's in-house Caliber 4130 — the column-wheel, vertical-clutch automatic chronograph that finally replaced the modified Zenith El Primero of the prior 16520. Housed in a 40mm Oystersteel case with an engraved tachymeter on the polished steel bezel, the 116520 is the last Daytona before the black Cerachrom ceramic bezel arrived in 2016, giving this generation a clean monochromatic profile that collectors increasingly recognize as a future classic. The black dial carries applied luminous hour markers with three contrasting subdials at 3, 6, and 9, the red "Daytona" script above the running seconds, and the screw-down Triplock crown flanked by screw-down chronograph pushers — engineering details that preserve 100-meter water resistance even with the chronograph engaged. Caliber 4130 delivers a 72-hour power reserve and carries Rolex's Superlative Chronometer certification, beating at 28,800 vibrations per hour through 290 parts and 44 jewels. With its 40mm diameter, slim chronograph profile, and Oyster bracelet, the 116520 wears comfortably for daily use while remaining the reference of choice for collectors who prefer the steel bezel over the later ceramic. Pre-owned, 2006 production.