Rolex. A stainless steel automatic bracelet watch Milgauss, Ref 116400GV, Purchased 20th April 2013Rolex. A stainless steel automatic bracelet watchModel: MilgaussReference: 116400GVDate: Purchased 20th April 2013Movement: 31-jewel Cal.3131 automatic, No.33190694Dial: Black, applied luminous filled baton hour markers, orange quarters, outer white minute divisions with orange five minute markers, polished baton hands with luminous inserts, orange lightning bolt centre secondsCase: Brushed and polished tonneau form, screw down back, inner cap, No.6282X1N0Strap/Bracelet: Fitted brushed and polished Oyster linkBuckle/Clasp: Signed folding clasp, stamped F2TSigned: Case, dial & movementSize: 40mm Accompaniments: Rolex box, outer card, international guarantee, brochures, swing tagThe name 'Milgauss' combines 'Mil', meaning a thousand, and 'Gauss' which is the unit for a measure of magnetism. Traditionally, most hairsprings are made of Nivarox which is susceptible to magnetism which has a detrimental effect on timekeeping. Now the Milgauss watch balance spring is made with Parachrom-Blu, which is unaffected by magnetism. Any watch that can withstand 4,800 A/m is considered "antimagnetic". This equals to approximately 60 gauss. The Rolex Milgauss is rated to withstand 1000 gauss because of its new technology in encasing the movement in soft iron, also known as a Faraday cage.