Borosilicate glass is a type of glass with the main glass-forming constituents silica and boron oxide. Borosilicate glasses are known for having very low coefficients of thermal expansion, making them resistant to thermal shock, more so than any other common glass. Such glass is less subject to thermal stress and can withstand the temperature fluctuations of the heated bed. Borosilicate glass is sold under such trade names as Kimax, Pyrex, Endural, Schott, or Refmex.
This new and improved flex-resistant glass plate is much stronger than the standard borosilicate glass plates and prevents flex during long prints. At 4mm thick, this new glass will hold up to the tremendous amount of force that large prints put on the build surface.