Channel is a kind of strip steel with a flute section. There is an instance for its size description now: 120*53*5, means the height of its waist is 120mm, the width of legs is 53mm and the thickness of waist is 5mm, or we can call it 12# channel. When there are kinds of channel with the same height of waist but different width of legs and thickness of waist, they must be differentiated by a b c, which is added to the right of the type no. Such as 25a# 25b# 25c# and so on.
