Angle ruler engineer square is fit for detecting angles and part marks. It is an industrial-grade, professional-grade tool for assembly and platform work. Precision machinist square is made of carbon steel, which has undergone heat treatment, high hardness, strong bearing capacity, and is not easily deformed under pressure. The plane angle of the base is 90 degrees inside and outside. It is used for right angle measurements. It can measure the vertical deviation of the inner and outer corners of the workpiece. The inside and outside of the square are true right angles, with an internal notch to ensure accuracy. This carpenter, machinist, square engineer, square can be used by DIY enthusiasts and professional businessmen. Material Carb.