Launched in 2017, the Greubel Forsey Grande Sonnerie is one of the brand’s most complicated and innovative timepieces. Wei takes a closer look at this repeater with a 43.5 x 16.13mm case, 72 hours of power reserve and a hand-finished tourbillon inclined at 25 degrees that completes a full rotation every 24 seconds. Its crisp chimes require a lot of energy, which is why the repeater mechanism has a dedicated barrel and can be set to one of three modes: grande sonnerie, petite sonnerie or complete silence.