https://www.ronstan.com/shacklewide-dpin-5-16-l-51mmw-28mm.html
Stainless Steel Wide D Shackle, 5/16" Pin, Coined Head | Ronstan Sailboat Hardware
Grade 316 stainless steel Wide D shackle, 5/16" diameter pin with a coined shackle pin head.
wide d shackle