As does the Reflecting Roadstud's manufacturer's website:
"The final component part of the “Catseye” is the cast iron base. Manufactured from Grey Iron, the cast iron base affords excellent protection to the rubber insert and has been specifically designed to withstand the demands of heavy traffic and effects of snow-ploughing."
"Cat's eyes are particularly valuable in fog and are largely resistant to damage from snow ploughs."
http://en.wikipedia.org/wiki/Cat%27s_eye_(road)
As does the Reflecting Roadstud's manufacturer's website:
"The final component part of the “Catseye” is the cast iron base. Manufactured from Grey Iron, the cast iron base affords excellent protection to the rubber insert and has been specifically designed to withstand the demands of heavy traffic and effects of snow-ploughing."
http://www.percyshawcatseyes.com/products/the-cats-eyes-road...