The iron casing insect sign nylon coil by material manufactures and so on PA6, PA11, PA12 becomes, these material's overall performance has guaranteed the product in use process security. Has the endophragm to be smooth, the compressed air or pneumatic brake responds quickly, the loss of pressure few, wear-resisting, bears characteristics and so on aging, good elasticity, widely uses in each kind of trailer tractor, the semitrailer, the trailer and all sorts of braking system's connection pipeline. The heat resistance is good, may in - 40℃ to 120℃ the environment under works. The product conforms to GB16897-1997, the national compulsory product authenticates the 3C authentication. Specification model: 22, 26, 28, 32, (coil diameter 110mm, 75mm) may have custom-made based on the customer demand.