... , ISO9001:2000, DOT certificate Air brake coil with double layer nylon :• Material:PA,PU,double nylon tube• Hose size(OD*ID):12×9 ... ,12×8, 8×6,10×7.5mm, 4-22mm etc.• Protection:spring ... air brake reinforced hose, air brake coil with double layerDouble tubing--Double layer nylon tube,double braided tube,reinforced tube Air brake coil with ...