... Channel. The indication of Type and Specification is Height (h)*Width (b)*Thickness (d). For example, 120*53*5 channel, means ... channel's Height is 120mm, Width is 53mm, Thickness is 5mm. Usually, we use centimetre data ... Heights are the same, but there are several width and thickness, we usually add "a", "b", "c" to the Height to distinguish ...