... , timber drive spikes, T-bolts, fish bolts, switch & crossing bolts, high tensile strength bolts for rail bridges etc.3, Various type and sizes ... drawing, please feel free to contact us for any possible business, thank you and look forward to the co-operation with you ... hardness:HRC:29-33 only for nut4- There shall be no crack and harmful defect on bolt and nut5-Surface dealing : Black, Grey ...