C-CHANNELS

C-section channel overcomes this by moving the web out to one edge of the flanges

While I-beams are strong, they're not always easy to incorporate into your fabrication. The problem is that you only have two parallel faces to mount to. Mounting to a face parallel to the web means adding an angle to the flanges. C-section channel overcomes this by moving the web out to one edge of the flanges, changing the cross-section from an "l" to a "C" in the process. C-section thus has three flat surfaces for mounting upon. It's still strong, although this geometry does give up a little of the rigidity of the I-beam. Against that, though, it avoids the use of brackets or angles. This, in return, saves money, time, and weight.