1. the standard length of the train rail is 12.5m and 25m.

2. round steel, wire, steel wire size to diameter d of mm (mm) number calibration.

3. the size of the square steel is calibrated to the millimeter (mm) number of the side length a.

4. hexagonal steel, octagonal steel size to the opposite side distance s of mm (mm) number calibration.

5. the size of the flat steel is calibrated in millimeters (mm) of width b and thickness d.

6. The dimensions of I-beam and channel steel are calibrated by mm (mm) of waist height h, leg width b and waist thickness d.

7. The dimensions of equilateral Angle steel are calibrated by the number of millimeters (mm) of equal side width b and side thickness d. 

    The dimensions of the non-equilateral angles are calibrated in millimeters (mm) of side widths B, b and d.

8. The size of H-shaped steel is calibrated by the mm (mm) number of web height H, wing width b and web thickness t1 and wing thickness t2.