Section 15 Base metals and articles of base metal 73 Articles of iron or steel 73 18 Screws, bolts, nuts, coach-screws, screw books... of iron or steel 73 18 14 Self-tapping screws of iron or steel Commodity Code Description 73 18 14 00 Self-tapping screws of iron or steel 73 18 14 10 Having a shank of an external diameter not exceeding 16 mm 73 18 14 90 Other