BCN3D Glass Printing SurfaceCompatible with Epsilon W50, Epsilon W27 and Sigma D25. It works for BCN3D printers with and without autocalibration. 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. The BCN3D glass printing surface has a calibration square which provides an excellent autocalibration for the printer and higher precision printing result.