Calibre 5 features a carbon-composite hairspring that was introduced in 2019, earning the movement the Isograph distinction. The trademarked name comes from the Greek word iso, which means “equal”, and refers to the stable and consistent movement of the component.
Known as the heart of the mechanical watch because of its importance in the overall function, the hairspring is the most difficult part to produce. A team of TAG Heuer mathematicians, physicists and chemists are behind the creation of this newly reinvented hairspring. The carbon-composite hairspring improves the performance of watches fitted with the brand’s chronometer-certified movement. The key benefits of TAG Heuer’s carbon-composite hairspring include the fact that the lightweight, low-density hairspring is virtually unaffected by gravity and shock and is completely antimagnetic. Perfect concentric oscillations are made possible thanks to the hairspring’s geometry and improve the precision of the watch. Optimal thermal behaviour and aeroelasticity have been achieved by pairing the carbon-composite hairspring with an aluminium alloy balance wheel. The carbon-composite hairspring is produced with the collet already attached. TAG Heuer is the exclusive manufacturer of these hairsprings, which are designed and produced in its in-house laboratory in La Chaux-de-Fonds.
It can be based on either the ETA 2824-2 (25 jewels) or the Sellita SW200 (26 jewels).