Features: 300L Capacity, 316 Grade Stainless Steel Material, Aluminum Frame. Inner Tank Material: The inner tank is made of food-grade SUS316L, ensuring high corrosion resistance and long-lasting durability. Insulating Layer: A 50-55mm thick, high-density polyurethane foam insulating layer reduces heat loss, maintaining water temperature efficiently. Vacuum Tube Tightness: With a vacuum tube tightness of P≤0.005 Pa, the solar water heater ensures minimal heat loss and optimal thermal performance.