If you open the pic fully, you can see the visor has some small markings on the side, which I've highlighted in red, which states when it must be used (i.e. daylight use only for not tinted, and daylight for tinted ones) and other certifications. It is common in almost even Vega helmets, which I had.
It is embossed and printed on the visor itself.
Cheers!
VJ
Comment