When sourcing sheet metal louvers, you must prioritize material grade, blade angle, and free area. For outdoor or corrosive environments, Stainless Steel (304 or 316) or Aluminum (6063-T5) are preferred over galvanized steel to prevent rust. The blade pitch and angle (typically 30° or 45°) determine the balance between airflow efficiency and weather protection. Ensure the material thickness (gauge) is sufficient to prevent vibration noise under high wind loads, usually ranging from 1.2mm to 3.0mm depending on the application.