When our Calibre SH21 movement was launched in 2014, its designer, Johannes Jahnke, promised that it would provide a canvas for him to experiment with further innovations and complications. The new C8 Power Reserve Chronometer shows this has now become a reality. With its DLC (diamond-like carbon) black case and dial, highly legible indexes and Arabic numerals, the C8 PR COSC carries with it many of the design cues of famous aviation timepieces like the Smith’s Mark II A clock found in the Spitfire. In truth, it feels more like a timing instrument than regular watch. The hand-wound version of our own movement is every bit as impressive as its automatic sibling. Thanks to its twin barrels, when fully wound, it'll deliver an incredible five days of power. Like the self-winding version of Calibre SH21, chronometer status is standard, while a power reserve complication – as promised in the name of the watch – counts down the time until the next wind.