1.SEAMLESS steel tube, 2. Production based on DIN2391, EN10305-1, EN10305-3 , 3. High precision on the tolerance of tube size. Packaging detail: PP ... .Standard: DIN2391, EN10305-1, EN10305-3.Steel grade: ST35, ST37, ST45, ST52, E235, E355.Tube OD: 5-80mmTube WT: 1.5-8mmCondition: BK ... certificate is sent together with goods. EN 10305-1 precision seamless steel tube