... wearability are extremely good, the coefficient of friction is low, nonpoisonous, the surface is smooth, can prevent getting rusty and forming silt ... size stability, penetrance little, resistance great, can leave no room for manoeuvre body of predestination use, it is verylong.Use way ... brake the fuel pipe, resistance great, can leave no room for manoeuvre body of predestination use, it is very long, ...