The R75 concept
R75 may sound complex, but it very basic at its roots: A simple tool allows everyone to visualize and easily understand for themselves. The R75 gauge demonstrates how Arai strives to maintain the R75 radius wherever possible. Move the gauge around the shell surface, as long as the two ends of the gauge are touching the surface, the shell conforms the R75 shape concept.
It’s not something most standards demand. It’s something ARAI demands.