C Shapes - American standard channels - C9x13.4

C shapes (American Standard Channels) have a C-shaped cross-section — two parallel flanges, tapered on their inner face, connected by a single web — giving the section one plane of symmetry rather than two. That asymmetry is exactly what makes channels useful: they're easy to bolt or weld flat along the web, pair back-to-back to form a symmetrical built-up member, or run singly where only one open face is needed. Typical uses include general framing, purlins and girts, bracing, stair stringers, edge trim on slabs and openings, and structural framing for trailers, truck bodies, and other equipment where a channel's flat web face simplifies attachment.