Slotted Channel What are the types?

There are black, electro-galvanized, hot-dip galvanized, stainless steel, aluminum alloy, zinc-aluminum-magnesium Slotted Channel

The color is black, original iron color. 

And there are two kinds of products: ordinary black slotted channel and pickling black slotted channel.

The ordinary black slotted channel has not any treatment after being released from the factory.There are iron filings and rust on the surface.

After corrosion treatment of the pickling black slotted channel , the excess impurities on the surface are corroded and leaked, and the surface is more neat and smooth.