Manganese: 0.8 – 1.2%. Chromium: 0.25% max. Magnesium: 0.8 – 1.2%. Silicon: 0.40 – 0.80%. Titanium: 0.15% max. Zinc: 0.25% max. FLAT & SMOOTH CUTTING SURFACE – All the aluminum plates are precisely cut and the surfaces are processed to be smooth and flat with no crack or airhole.