The square ruler class includes 90 ° specialized tools such as square rulers and bending plates, which are suitable for measuring the verticality of machine tools, mechanical equipment, and components, installation, processing, positioning, marking, etc. It is an important measuring tool in the mechanical industry. Pay attention not to use and store T-shaped groove bending plates in damp, corrosive, high and low temperature environments. Before using T-shaped groove bending plates, the installation and debugging of the bending plate should be carried out first, and then the working surface of the T-shaped groove bending plate should be wiped clean. After confirming that there are no problems, use the bending plate.