The Calibre-Maker is a watchmaker specialized in assembling and adjusting movements, also known as Calibres. Once the drawings have been finalised and the manufacturing plans precisely defined, it is possible to proceed to building a run of prototypes, generally ten or so. They are subjected to testing which can last from four to twelve months. Only after these trials are completed can the movement go into production. The care required at each step of this phase demands a considerable investment in time. For more complicated models, final approval of prototypes can take up to two years.