D shackles are made from grade 304 stainless steel and grade 316 stainless steel, ss316 is better than ss304 in corrosion resistance and rust prevention, if their application areas are very bad like marine and biogas..., we recommend you choose grade 316 stainless steel, if not, ss304 is good enough. D shackles are available in size from 4mm to 32mm, their detailed dimensions and working load limits are below for your reference. D shackles are produced by hot forged, surface is mirror polished. If you have any other questions about d shackles, please feel free to contact us, you could find our contact information.