The annual calendar chronograph is one of the most fascinating yet rarest combinations in the industry, as we’ve experienced in this in-depth article. And one brand in particular does it better than the rest of the bunch, and that is Patek Philippe. For a good reason, since the brand invented the annual calendar function back in 1996. Now, there’s a rather large collection of watches using this unusual combination, and specifically the 5905 is often regarded as the most attractive model. Today, Patek launches a new, surprisingly sporty version of this watch with a steel case, a steel bracelet and an olive green dial, with the new Chronograph Annual Calendar 5905/1A.While on paper we’re certainly talking about just a new version of a watch that has been in production for some years now, this new iteration of the large Chronograph Annual Calendar, the reference 5905/1A, comes with some rather interesting attributes. Yes… steel case and bracelet, not something that common at Patek (at least not in the range of watches). The 5905 is a modern watch, with a 42mm diameter, which combines two of Patek’s finest complications; the annual calendar function (which they invented) and the chronograph. Previously available in rose gold with a chocolate dial or in platinum with a blue or black dial, the 5905 is revamped this year in a rather surprising combination. And if the specifications and proportions are identical (42mm diameter and 14.13mm height), the case has been given a commoner material, stainless steel – which is somewhat the exception for Patek Philippe, even though we’ve seen more and more steel models recently. Entirely polished, with a convex bezel and rectangular pushers, it is a rather large watch with heft and presence. Modern and sleek, it is now combined with something entirely new for this range, a 3-link stainless steel bracelet with a folding clasp. This combination results in a look that is drastically different from the previous editions in precious metals. Ad - Scroll to continue with article As for the dial, the display remains identical. Central hours and minutes, no running seconds, a sub-dial at 6 o’clock that is used as a practical 60-minute counter for the chronograph, a central chronograph seconds. And of course, there are the 3 windows on top for the annual calendar function, positioned in a very European (so I’d say natural… sorry US readers) way, with weekday, date and month indications. Finally, a small round aperture in the sub-counter is used as a day-night indicator.New to this model, but not to Patek – think about the final edition of the 5711 – the new Chronograph Annual Calendar 5905/1A comes with an attractive sunray-brushed olive green dial. All elements of the dial are white gold (hands and applied markers) or white for the numerals and tracks, resulting in a rather sleek and sporty look.Powering this watch is the same in-house Calibre CH 28-520 QA 24H, a modern automatic chronograph with an annual calendar module on top. It relies on an integrated construction and the chronograph functions are actuated by a column wheel and a vertical clutch. It also features a flyback function. With its Patek Philippe Seal certification, the decoration is superb and, although a central rotor partially hides it, the view through the caseback is pleasant. The frequency is 4Hz and the power reserve is given for 45-55 hours.The Patek Philippe Chronograph Annual Calendar 5905/1A stainless steel and olive green dial will be part of the permanent collection and priced at EUR 51,500. More details at patek.com.