A36 hot rolled steel channels have a rough, blue-grey finish. A36 material is a low carbon steel mild steel which is long lasting and durable. Hot rolled C channels have a "structural shape" meaning at least one dimension (excluding length) is greater than 3 inches. C channels inside flange surface have approximately a 16-2/3% slope, which distinguishes them from "MC" channels. Common applications include structural support, trailers, and other architectural uses. ASTM A36 / A36M-08 is the standard specification for carbon structural steel.