Polyethylene in one of the forms mentioned in note 6(b) to this chapter, of a specific gravity of 0,958 or more at 23 °C, containing: - 50 mg/kg or less of aluminium, - 2 mg/kg or less of calcium, - 2 mg/kg or less of chromium, - 2 mg/kg or less of iron, - 2 mg/kg or less of nickel, - 2 mg/kg or less of titanium and - 8 mg/kg or less of vanadium, for the manufacture of chlorosulphonated polyethylene