Over15 years sourcing drinkware from China, I’ve learned that skipping these 5 checks almost always leads to problems: Factory’s Core ExpertiseNot all factories are equal. Some specialize in stainless steel, others in glass ，aluminum. Match your product to the factory’s core strength. Quality Control ProcessAsk: Do they have in-line inspection? What’s their defect rate? Who checks before shipping? Communication ResponsivenessA factory that takes 3 days to reply during sample...