When sourcing rain shoes, the primary materials are PVC (Polyvinyl Chloride), Natural Rubber, and EVA (Ethylene Vinyl Acetate). Natural rubber offers superior flexibility and environmental friendliness, while PVC is more cost-effective and chemical-resistant. Ensure the upper and sole are bonded via one-piece injection molding to eliminate seams, which is the most effective way to prevent leakage. For the lining, prioritize breathable mesh or cotton to enhance user comfort and prevent moisture buildup inside the shoe.