Every CALIBRE begins as a bare plate and a question: how little can we remove before the watch stops being honest? The answer lives in the caliber — the engine of springs, wheels, and jewels that turns stored energy into measured time. In this piece we trace a single mainspring's unwinding, from the barrel to the balance, and explain why a 60-hour reserve is a design decision, not a marketing number. It starts at the barrel. A coiled mainspring, wound by the rotor every time the wrist moves, pushes against the gear train with a force that fades as it unwinds. Most of the work in a good caliber is spent keeping that fading force from showing up on the dial. Next comes the escapement — the pallet fork and escape wheel that release energy in small, even steps. Each tick you hear is one of those steps. Our Cal. C-01 beats at 28,800 vibrations an hour, regulated in six positions so the rate stays steady whether the watch lies flat on a desk or hangs on a moving wrist. Then the balance, the true heart of the thing: a weighted wheel and a hairspring breathing in and out eight times a second. We could have chased a longer reserve with a bigger barrel and a thicker case. We chose 60 hours because it carries a watch from Friday evening to Monday morning in a case that still slips under a cuff.