Built-in spiral wire，With spiral steel wire resistance to negative pressure and bending，Strong scalability，Constant silk softness and resistance to cold and heat -15 degrees without stiffness，Thick wall，The Inner is smooth，The inner wall of the tube is smooth, with a ring of steel wire around the water flow more smooth，High pressure forging steel wire surround with sufficient oil and acid and alkali resistance，High quality PVC material, good performance, heat resistance and cold resistance, refuse aging