● Pre-galvanized square/rectangular tube: Pre-galvanized square/rectangular tube is made of hot dipped galvanized steel strip directly.

● Hot dipped galvanized square/rectangular : Hot dipped galvanized square/rectangular tube owns thicker zinc coating than pre-galvanized square/rectangular tube. Black tubes will be dipped into zinc pool for galvanizing.

● Electro galvanized square/rectangular : The technology of electro galvanized square/rectangular tube is similar to hot dipped galvanized tube, but the thickness of zinc coating is less than hot dipped galvanized tube.

● Painted square/rectangular:Painted square/rectangular to remove the rust and clean the oil first and then paint the required color paint.