Okay just what is THAT?
Castration bander— used in castrating pigs, sheep,etc. The rubber bands are extremely tight—the hand device spreads them for wrapping them around the uh... goodies.
The elastic is so tight it cuts off blood supply to testes, and kills them off— they die. Then they can be left to be absorbed into the body, or they can be cut off with a minimum of blood loss.