Helmet top level materials and workmanship. A little disappointed because my "big" ears just fit in the internal cavities of the atria. Indeed, hexagonal "crushed" 6 cm X 3.5 cm, cavities "circum aural" are a bit tight for my ears comfortably (width and depth a fair bit). Hence a compression effect, limiting helmet porting time, even if the foam is also comfortable. Further noise reduction is quite limited.
