JAEGER-LECOULTRE REINTERPRETS THE MASTER ULTRA THIN POWER RESERVE

Jaeger-LeCoultre Calibre 938 Revised to Provide a 70-Hour Power Reserve

In line with La Grande Maison’s pursuit of timekeeping precision, together with added utility for the user, the Manufacture constantly improves its in-house calibres in line with advancing technology. Calibre 938 has been significantly revised to power a new generation of timepieces. Most notably, the power reserve has been increased to 70 hours – long enough to leave the watch aside for an entire weekend and wear it again on Monday with no need to rewind it or reset the time.

This significant gain in power reserve has been achieved without adding to the size of the calibre, which remains 4.9mm thick. The mainspring barrel was redesigned, some key components are now made of silicon, which makes energy transmission smoother by reducing friction of the moving parts, and other minor changes have been made to bring greater reliability.

The power reserve function is a signature complication of Jaeger-LeCoultre, pioneered by the Manufacture in 1948 with the introduction of Calibre 481. The Powermatic, recognised by its distinctive red-and-white indicator, was the world’s first self-winding timepiece with a power reserve gauge and quickly became a key model for the Manufacture in the early 1950s. The Master Ultra Thin Power Reserve is equally recognisable, with the distinctive design of the power reserve display complemented by date and small seconds indicators – the three complications bearing witness to the complexity of the calibre and the technical savoir-faire of Jaeger-LeCoultre’s watchmakers.