Thanks to Simon Patterson from MCN, here's FIM's technical director, Danny Aldridge, and his magic box, designed for monitoring the evolution of aerodynamics in MotoGP.
Until last year, every new project was subjected to its own assessment standards. Starting in 2019, however, bikes with fairings will have to enter this sort of aluminum box to make sure they meet the required standards.
It is practically a template on a 1:1 scale that establishes the measurements allowed for protruding and obstructing components. Surely, a less subjective and less interpretable system for these types of assessments.