Case: Three-body, polished and brushed, signature reflector, screwed- down winding crown and case back engraved: Rolex Oyster - Milgauss, special anti-magnetic shield, sapphire crystal. Dial: Black with applied orange and beige color steel baton indexes, outer minute/seconds track with orange 5-minute Arabic markers. Luminous white gold baton hands, orange lightning seconds hand. Movement: Cal. 3131, rhodium-plated, fausses cotes and oeil-de-perdrix decoration, 31 jewels, straight-line lever escapement, monometallic balance adjusted to temperature and 5 positions, shock absorber, self-compensating free-sprung Breguet balance spring, Microstella regulating screws, hack mechanism.Dial, case and movement signed. DIAM. 40 mm. THICKNESS 13 mmDial, case and movement in good conditionNOTE: The Rolex Oyster Perpetual Milgauss is a model introduced by Rolex in 1955 with the reference number 6543 (produced until 1957) and subsequently amended in 1956, with the reference number 6541 (produced until 1962).The Milgauss was designed as anti-magnetic watch specifically for those working in power stations and in research labs in which electromagnetic fields can cause damage to watches.It is equipped with antimagnetic alloys and enclosed in a Faraday cage. The word is derived from Milgauss thousand, which means a lot in French, and Gauss, the unit of magnetic field.