He continued: "It is not unusual for Rolex to make incremental improvements to their calibers. The 1500 series went through multiple iterations over its long history. The 3000 series received small improvements, tweaking part tolerances. All of the ladies' calibers have also seen small improvements over the years. That's the Rolex way. Continually improving things, down to the smallest details. The upgrades to the 4130 haven't been mere tweaks, however, they bring notable improvements."

"An 'upgrade' they did make some noise about was the blue Parachrom hairspring. As alluded to above, earlier 4130s were equipped with a white 'Parachrom' hairspring built on the same molecular foundation. Once proven and, in light of cutbacks from Swatch Group and its subsidiaries like Nivarox, it was important for Rolex to market this milestone in their vertical integration of production. More importantly, to me, the Parachrom hairspring was a serious horological leap forward in terms of precision and reliability of timekeeping."

"They made a small upgrade to the train wheel bridge, modifying some of the components and the way that they operate upon it, to improve the reliability of the hour and minute counters. I would class this upgrade as being similar to the minor upgrades made to previous generations of Rolex movements."

"A more notable upgrade that they introduced is a hairspring protection block, which eliminates any possible risk of the lower coils of the hairspring tangling in the hairspring's overcoil when the watch endures a hard blow. To the best of my knowledge, this was a horological first. I have never seen anything like it from any other watch company. It is stunningly brilliant in its simplicity and it does its job flawlessly. While the wearer of a Daytona may never notice it's there, they would quickly notice if it were not should the watch take a hard knock."

"The biggest incognito upgrade are playless gears in the chronograph system. As I'm sure you already know, the vertical clutch system of the 4130 eliminates the jarring start of the second that can be noticed on chronographs that feature a lateral clutch when the chronograph is started. Playless gears take this to the next level, by eliminating backlash between gear teeth. In simple terms, backlash is a small amount of space, or 'play,' between the teeth of two gears that are interacting with one another, so that one tooth can disengage as another tooth moves in to continue to the transfer of energy."