The MOSAIC project brings together the design and analysis work done on all previous conceptual designs for a MOS for the ELT. As we saw in previous section, the MOSAIC Consortium includes world-leaders in the design, development, and construction of astronomical instrumentation, located across Europe and Brazil, and supported as high priority by their funding agencies. Partners within the MOSAIC consortium have a long and successful heritage of instrument delivery for ESO, including: FLAMES, KMOS, MUSE, SPHERE, NACO, VIMOS, and X-SHOOTER. This makes available the skills needed to develop MOSAIC whatever the area: Adaptive Optics, Fibres, Spectrograph, Interfaces with the telescope, etc. The MOSAIC instrument concept is now under development and will provide a versatile, facility-class instrument, capable of addressing a broad range of key science topics enabled by the size and adaptive optics of the ELT. Following Figure 3-1 illustrates the skills of the consortium especially with respect to Spectrographs and Adaptive Optics: