In a partnership between Phillips, LVMH-owned Zenith, and renowned independent watchmaker, Kari Voutilainen, a never-before-sold series of vintage Zenith 135-O movements (regulated by Charles Fleck and René Gygax in the mid-twentieth century for observatory trials) are being expertly finished, cased, and brought to market.

Featuring a stunted escape wheel to accommodate a larger balance wheel for improved rate stability, the movement architecture is akin to the Peseux 260, another vintage, observatory-grade chronometer, which Voutilainen based his own series of Observatoire timepieces on. However, unlike the Peseux 260, the Zenith 135 has an extra pinion in the gear train for a center-seconds hand, and can readily be set up to indicate either central seconds or subsidiary seconds. Whereas the Peseux 260 is architected specifically for a sub-seconds layout. That said, like Voutilainen's Observatoire timepieces and as with the Zenith 135-equipped timepieces that have preceded this set, Zenith has opted to go with sub-seconds.

It's also worth noting that, while Voutilainen converted the Peseux 260 to a free-sprung balance system for improved isochronism, he was very intentional about his team leaving the regulating components in the Zenith 135-O calibers they received exactly as they found them:

“The persons working on these movements were the best watchmakers at the time. They had the know-how to make things precise. That precision doesn’t disappear after 70 years. Our duty was not to touch that performance.”