Classification of composite plastic articles: predominance of weight and value determines tariff heading and exemption entitlement. Classification of composite articles of plastic and non-plastic materials depends on the predominance of weight and value of component materials and trade identity under the Rules of Interpretation; if so classified as an article of plastics for the relevant periods the product is entitled to the notification exemption because relief is not limited to exclusively plastic goods. Polyurethane foam produced in situ during manufacture is dutiable and its classification is for the jurisdictional collectorates to determine.