Smilley! good question! Hi everyone
In a nutshell (sorry couldn't resist!) you want to use materials according to the risk involved, so here we need to look at the mass/volume of objects with relation to our heads, That ball needs to be stopped, avoid any penetration and deformity and then get rid of it asap so we need to look at thigh pad technology rather than Headkayse/Enkayse which is mainly for when you come into massive mass (head onto the curb/floor) and more of a deceleration / cushion effect.
So, Stretton Fox tech in these does nicely! theres some preview pics on their way to Arytek and a short video popping up soon)