In the Guangzhou hair market, products are often categorized by 'grades' (e.g., 8A to 12A), though these are not universal standards. You should focus on the material source (Virgin, Remy, or Non-Remy). Virgin hair is the highest quality, as it is chemically unprocessed and has intact cuticles. Remy hair ensures cuticles are aligned in one direction to prevent tangling. Always verify the ratio of long hairs within a bundle; 'Double Drawn' hair provides consistent thickness from top to bottom, whereas 'Single Drawn' is thinner at the ends.