When sourcing waterproof tents, the most critical metric is the Hydrostatic Head (HH) rating, measured in millimeters. For professional B2B sourcing, ensure a minimum of 1,500mm for basic rain protection and 3,000mm to 5,000mm for four-season or heavy-duty use. Additionally, verify the denier (D) of the fabric (e.g., 210D Oxford or 70D Nylon); a higher denier indicates better tear resistance and durability. Look for PU (Polyurethane) or Silicone coatings, as these provide the primary water barrier.