Cast iron square material: cast iron square by GB6092-85 standards, HT200, mainly used for workpiece inspection and crossed at right angles, in the installation and repair of equipment, inspection related to parts or components of verticality. According to the GB6092-85 standard, HT200-250 material, mainly used for workpiece inspection and crossed at right angles, in the installation and repair of equipment, inspection related to parts or components of verticality.