The truth is that the original shell is made in MAT glass & polyester resin. Overall thickness is around 1,5mm. but an upper area 10cm.x10cm. wide made with multiaxial glass 6mm. thick (just where the impact test is made, according to the euro test regulations).
Unfortunately, I find the strenght of such area of very little use, because my neck wouldn’t survive anyway to a vertical impact. It could be useful just if someone let drop a brick or similar from a window.
Schuberth is just following the rules. If the helmet should pass the same test on other sides, it would weight 3 kg.
Now I got an helmet that is able to pass the euro testing in all directions with the same weight of the original one.
As usual in this forum, everybody is free to understand what I say, in his favourite way.