Malleable Iron Shell Block Double Sheave With Shackle-LG RIGGING®, also known as Malleable Double Sheave Shackle Pulley.
Pulley and Block are common lifting mechanisms used for rigging and can be used for Manila Rope, not for Wire Rope.
The surface finish is Hot Dip Galvanized, so it could be anti-corrosive, which we usually use in Ocean Operations.