People who are interested in these early tourbillons are also generally aware of Omega’s 19 jewel, caliber 30 I tourbillon movements. There were 12 made in total and all were 30mm in diameter, so as to allow them to compete in the wristwatches category at the Geneva observatory competitions. Until recently, it was generally believed that they were not actually cased until 1987, when seven of the twelve movements were discovered by Omega, refinished and rebuilt, cased as wristwatches, and sold to collectors. One of these is still in the Omega Museum. However, the example Phillips has on offer is in a steel case, and appears to have the distinction of having been cased in 1947 as a prototype wristwatch.