CRP Antibacterial? SD steel is a pre-painted steel manufactured from continuous hot-dip process. Its metal coating layer contains Zinc(Zn) as the main metal with aluminum (Al) (approx.11%) , magnesium (Mg) (approx 3%). CRP Antibacterial? SD steel, Superior corrosion resistance under conditions of low temperature and high humidity. Suitable for forming a wall insulation panel for cool room (low temperature) in the food manufacturing and food processing. Steel life-time and reduce long term maintenance cost.