14 Precious metals and their alloys and goods in precious metals or coated therewith, not included in other classes, namely, filters for catalytic converters or emission control, membrane electrode units, polymer electrolyte membranes, and mobile emission control apparatus coated with gold, iridium, osmium, palladium, platinum, rhenium, rhodium, ruthenium, or silver; precious metals in the form of bars, ingot, powder, medallions, non-monetary coins