When selecting GI C iron channels, size is a vital consideration. The dimensions of these channels influence their load-bearing capacity, installation ease, and compatibility with other structural components. Typically, the size of a GI C iron channel is described by its height, width, and thickness. Common sizes range from smaller channels of approximately 41mm height and 41mm width to larger channels reaching over 100mm in height and width. The choice of size will depend on the specific requirements of the project, including the weight of the systems to be supported and the spacing between supports.