ESO has signed a contract with the French optics company Reosc, a subsidiary of Sagem, Safran group, to manufacture the deformable shell mirrors that will comprise the fourth mirror (M4) of the European Extremely Large Telescope (E-ELT). These mirrors will be mounted and supported in the adaptive mirror unit (ann15045) to form the largest-ever adaptive mirror unit in the world. The contract was signed by representatives of Reosc and ESO at a ceremony at ESO Headquarters on 8 July 2015.