valve steel ev4=suh37=21-12n Size:4.8mm--12.7mm 20 years engine valve steel ... factory ISO certification valve steel ev4=suh37=21-12n Size:4.8mm--12.7mm20 years engine valve steel factoryISO ... SUH1, SUH11, SUH37, SUH31, SUH35, NCF751, NCF80AAbbreviated NameXB, MF811, 21-12N, 23-8N, 21-4NWNb, 21-4N, ResisTEL, 751, 80A Factory ... -83781518Cell phone: 86-13182223650 valve steel ev4=suh37=21-12n