Only if necessary!

The mark must be in the form of a square set at an angle of 45° (diamond-shaped) with each side having a length of at least 50 mm, the width of the line must be at least 2 mm and the letters and numbers must be at least 6 mm high. The proper shipping name "Biological substance, Category B" in letters at least 6 mm high must be marked on the outer package adjacent to the diamond-shaped mark.