The 300 g/m² weight threshold is a classification bright line: lighter fabrics (511111) typically include dress-weight and lighter suiting cloths, while heavier fabrics (511119) cover coating and overcoating weights. Accurate weight measurement per square meter is essential because the duty rate can differ between the two subheadings.

If the fabric contains carded wool or fine animal hair mixed with manmade staple fibers, it falls under subheading 511130 rather than the pure-wool subheadings. The blend composition by weight determines which subheading applies, and the chapter notes govern how mixed-fiber fabrics are assigned when no single fiber meets the 85% threshold.