When purchasing shoes in bulk, you must prioritize material durability and construction integrity. For outsoles, look for high-abrasion rubber or slip-resistant TPU with a hardness rating suitable for the intended use. For uppers, verify if the material is genuine leather, high-grade PU, or breathable fly-knit mesh. Ensure the bonding strength (sole-to-upper) meets international standards to prevent delamination, and check that insole cushioning (EVA or Memory Foam) provides adequate density for long-term wear.