Nylon air brake spiral hose and seven-core cable helix protected by nylon hose are the best way between semitrailer's main engine and trailer as the air brake pipeline and electrical circuit connecting. Smooth inner wall,fast response to brake,less pressure loss,good stretch and recovery performance.Nylon tenacious nature and spiral design scalability make the possibility of hose damage min.and the working life longer than other connecting way.If needing rapid recovery,the length pulled should not exceed half the original length.Great withstand voltage ,min. burst pressure:49Kg/cm2.When allowing the safe factor is 4:1,the temperature is 50℃,recommended working pressure is up to 9Kg/cm2.