The Greubel Forsey Double Tourbillon 30° was introduced to the market in 2004 after four years of research and development. This revolutionised timepiece features a patented tourbillon system, which a tourbillon is set within another tourbillon. The exterior tourbillon is inclined at 30° and rotates in 60 seconds and the inner tourbillon carriage rotates every four minutes. This ground-breaking invention permanently compensates the rate of gravity-induced errors in the escapement and oscillator system. The 30° inclination ensures a better chronometric performance while maintaining an acceptable depth to the watch. The anthracite dial displays a glazed aperture that reveals the technical marvel of this innovative complication in motion. Offered in excellent overall condition and complete with original certificate and fitted presentation box, this present watch represents a milestone in the manufacture of tourbillon wristwatches.