The master watchmakers in La Chaux-de-Fonds have reinterpreted the tried and tested GP01800 in-house calibre, adding a sizeable dose of cutting-edge technology. It is fitted with a variable-inertia balance. Most watches feature an index regulator which alters the effective length of the hairspring, making the watch run faster or slower. With a variable-inertia balance, the length of the hairspring is fixed and the rate is altered by adjusting the inertia weights fitted to the spokes of the balance wheel. This system delivers greater stability as well as superior shock resistance. Girard-Perregaux has used silicon to make the escapement and parts of the balance wheel. While silicon is used by some companies, it remains rare despite its many advantages. It is not liable to corrosion, is unaffected by changing temperature, lightweight and less susceptible to magnetic fields. These attributes confer an array of user-benefits. For example, where some parts made of conventional materials can behave differently at various temperatures, silicon components remain unaffected, delivering consistent timekeeping. In addition, silicon’s low coefficient of friction mitigates both wear and energy consumption.