The description of the item 3815199020 of Germany HScode: Supported catalysts, n.e.s. (excl. supported catalysts with precious metal, a precious-metal compound, nickel or a nickel compound as the active substance and catalysts in the form of grains of which >= 90% by weight have a particle-size <= 10 micrometres, consisting of a mixture of oxides on a magnesium-silicate support, containing by weight >= 20% but <= 35% of copper and >= 2% but <= 3% of bismuth and of an apparent specific gravity of >= 0,2 but <= 1,0) : Catalyst, -|in the form of solid spheres, -|of a diameter of 4|mm or more but not more than 12|mm, and -|consisting of a mixture of molybdenum oxide and other metal oxides, supported on silicon dioxide and/or aluminium oxide,for use in the manufacture of acrylic acid