U bolt for truck wheel supporting spring 45# or 40Cr Heat treatment:thermal refining Surface:Bake paint, Zinc plate,Phosphati 7800001 U BoltU bolt for truck wheel supporting springMaterial: 45# or 40CrGrade: 4.8/8.8/10.9Heat treatment: thermal refiningSurface:Bake paint, Zinc plate,Phosphating 7800001 U Bolt for truck wheel supporting spring