When sourcing waterproof plastic bags, the material composition determines durability and clarity. You should prioritize LDPE (Low-Density Polyethylene) for flexibility and moisture resistance, or PP (Polypropylene) for high clarity and heat resistance. Ensure the thickness is specified in microns; for heavy-duty industrial use, a thickness of at least 60-100 microns is recommended to prevent punctures. Additionally, verify if the material is BPA-free and food-grade if the bags are intended for food packaging.