Section 15 Base metals and articles of base metal 72 Iron and steel 72 18 Stainless steel in ingots or other primary forms;semi-products of stainless steel 72 18 91 Of rectangular (other than square) cross-section 72 18 91 00 Of rectangular (other than square) cross-section Commodity Code Description 72 18 91 00 000 Of rectangular (other than square) cross-section