Customs duty cap limits basic import duty on specified heading 52.01-52.03 goods to an ad valorem rate. Prescribes a cap on basic customs duty for imports of goods under tariff headings 52.01, 52.02 and 52.03 by exempting that portion of duty which exceeds the stated ad valorem rate, thereby limiting the amount of duty leviable under the First Schedule to the Customs Tariff Act for those specified headings at importation.