MB M13.21

Manually wound monopusher chronograph movement with column-wheel and horizontal coupling. Measures 29.50 mm in diameter and 6.40 mm in height, comprising 239 components and 22 jewels. Offers a 55-hour power reserve, a 11.40 mm screw balance with a 26 mgcm² inertia, and an 18,000 A/h frequency. Features a Phillips terminal curve hairspring, rhodium-coated German silver plates and bridges with Côtes de Genève, circular graining, and hand-chamfered edges, plus a gold-coated, diamond-hubbed going train.