... softness and flexibility,environmental and nontoxic material. Spring air hose: • Material:PA,PU etc. • Hose size(OD*ID):12* ... 9,12*8,8*1, 4...22mm or others • Protection:spring or plastic • O.D. of turn:110,90,80,70 ... TubeTubing -- PA (Polyamide, Nylon) TubeTube-- PU (Polyurethane) TubeTubing -- PU (Polyurethane) air brake coils