Unlike the most ancient and original open-air acoustic shells made of stone in roman amphitheatres, today's acoustic shells used in performance rooms have to be versatile and discreet, so that their presence does not hinder the use of the space for the most varied types of performances. Our shells have been developed and built with light and attractive materials, which facilitate as much as possible their practical use. They adapt to the orchestra by increasing the number of the necessary modules and by adjusting their application according to the type of performance. It is a stage equipment that is easily assembled and disassembled and that is imperceptible when it is not being used.