When sourcing raincoats, the most critical technical factor is the Waterproof Rating (measured in mm). For light rain, a rating of 5,000mm is sufficient, but for industrial or heavy-duty use, look for 10,000mm to 20,000mm. Additionally, evaluate the Breathability (Grams/m²/24hrs) to ensure user comfort; a rating of 5,000g/m² or higher is ideal for active use. Ensure the construction features Heat-Sealed or Taped Seams to prevent water leakage through needle holes, and prioritize materials like TPU-coated polyester or PVC for durability.