One chain, 8mm high strength stainless steel (braking load
5 ton, W.L. 1,3 ton.)
Today we don't use the swivel, the chain is directly connected to the anchor
using only the shackle on the photo.
Notice the position of the shackle, it's
important for various reasons to mount the shackle the right way, not
introducing unnecessary forces on to the shackle and anchor.