Antique Plantation Slave Shackles

Quoted from eBay auction: "These shackles were used on the Rotherwood Plantation in East Tennessee in the 1850's. The master of Rotherwood plantation was a cruel man who owned many slaves. The screw lock is very rusted and is VERY hard to open. Also included is some sort of cotter pin or shackle pin. I can't figure out how it is used but it came with the shackles."