When evaluating denim, the most critical factor is Weight (measured in Ounces/oz). For men's jeans, 12oz to 14oz is standard for durable, classic styles, while 8oz to 10oz is preferred for lightweight summer collections. You must also verify the Composition, specifically the percentage of Spandex (Elastane); a 2% to 3% blend is essential for 'stretch denim' to ensure wearer comfort and shape retention. Additionally, check the Yarn Count (e.g., 7x7 or 10x10) and the Weave Construction (3/1 Right Hand Twill is most common) as these dictate the fabric's texture and strength.