What is the material of the Steer Rack return pipe?

   Brake oil pipe material : 1, brake hard (oil) pipe (the material is mainly 20 steel and copper pipe. 2. Brake soft (oil) pipe (the material is mainly nylon pipe PA11, and nitrile rubber pipe with intermediate braid layer); Steering power supply oil pipe: 1. Turn to high-pressure oil inlet hose, low-pressure oil outlet hose (the main material is rubber). 2. The material of the power supply hard pipe is aluminum; Fuel pipe: 1. Oil outlet hose (the main material is rubber or nylon). 2. Oil return hose (the main material is rubber or nylon). Tank to filler hose (the main material is metal or rubber or plastic).