In the wholesale market, quality is usually categorized into grades such as A, AA, AAA, or 1:1 Mirror Quality. For professional sourcing, you must prioritize 1:1 quality which uses original-grade fabrics (e.g., 100% combed cotton or high-thread-count mercerized cotton). Pay close attention to the GSM (Grams per Square Meter); a premium heavy-weight shirt should be between 220-260 GSM. Additionally, inspect the stitching density, ensuring at least 10-12 stitches per inch to prevent fraying and maintain the garment's shape after multiple washes.