When sourcing PP bags, especially woven polypropylene (WPP), you must evaluate the GSM (Grams per Square Meter), which determines the fabric's strength and thickness. For heavy-duty applications like grains or chemicals, a GSM of 70-120 is standard. Additionally, check the denier count (yarn thickness) and the mesh density (e.g., 10x10 or 12x12) to ensure the bag can withstand the required load-bearing capacity. For outdoor storage, ensure the bags are treated with UV stabilizers to prevent degradation from sunlight.