Channel steel: Channel steel is a long strip of steel with a trough-shaped cross section. Its specification representation method: for example, 120*53*5 means channel steel with waist height 120mm, leg width 53mm and waist thickness 5mm, or 12# channel steel. For channel steel with the same waist height, if there are several different leg widths and waist thicknesses, a b c should be added to the right side of the model to distinguish them, such as 25a# 25b# 25c#.