When purchasing stock lots, you must verify the fabric composition, typically a blend of cotton, polyester, and spandex (elastane). For high-quality stretch jeans, a spandex content of 2%-5% is ideal. Pay close attention to the fabric weight, measured in ounces (oz); 10oz-12oz is standard for four-season wear. Additionally, inspect the wash process (e.g., stone wash, enzyme wash, or acid wash) to ensure color consistency across the batch and check that reinforcement stitching is present at high-stress points like the crotch and pockets.