We are offering center bolts. Specifications: thread size: m8 to m20, 516 to 34" length under the head: 35mm to 550mm, 1.12" to 22 thread: i.s.o. Metric (fine & rough), unf unc material: low carbon steel, aisi 1010, en 8aisi 1035, en 8daisi 1045, en 15aisi 1541 i.s.o. Material strength grade: 4.6, 5.8, 6. 8, 8. 8 sae material strength grade: 2,