A Stainless Steel triple calendar chronograph Wristwatch with Phases of the Moon and Registers, Universal Genève, 'Tri-Compax, Circa 1955

nickel lever movement, 17 jewels, monometallic compensation balance, precision regulator, silvered brushed dial, applied baton indexes, dauphine hands, four engine-turned subsidiary dials indicating date combined with phases of the moon, constant seconds, 30 minutes and 12 hours register, tonneau water-resistant-type case with raised bezel, fancy downturned faceted lugs, two round chronograph buttons in the band, screw back, case, dial and movement signed.

It is believed that this model, the 'Tri-Compax' with screw back, water-resistant-type case, was first released in 1953.