For heavy-duty river tubing, prioritize Heavy-Gauge PVC (at least 0.50mm to 0.80mm thickness) or K80 PVC to ensure puncture resistance against rocks and debris. If the tube is intended for rental or rugged environments, look for models with a 600D to 1000D Nylon or Polyester fabric cover, which provides an extra layer of protection and UV resistance. Ensure the seams are High-Frequency (HF) Welded rather than just glued, as welding creates a permanent, airtight bond that prevents leaks under high pressure.