... truck,trailer,tractor and so on. Trailer air brake hose,spring air hose,air brake hose: • Material:PA,PU etc. • Hose size(OD ... *ID):12*9,12*8,8*1, 4...22mm or others • Protection:spring ... -- PA (Polyamide, Nylon) TubeTube-- PU (Polyurethane) TubeTubing -- PU (Polyurethane) air brake coils