These beads are coated with a special coating during the manufacture of the glass beads.
In the rainy and foggy weather, the moisture can not easily adhere on the surface of glass beads,
so the effection on reflectivity caused by bad weather will be reduced.
The granulometry of this type glass beads is the same as non-coated glass beads.
The glass bead can be produced based on the standard of countries or areas,
such as EN1423/1424, AASHTO M247, BS6088, JIS R3301 and KS L2521 etc.