To hang toys, simply hang the toy by it's chain in the U shaped loop and screw the stainless steel ball on from the outside of the cage.  Anytime your Parrot attempts to unscrew the toy hanger, the ball simply spins around on the outside of the cage.  This device can also be used as a keyless cage lock on cages that accept a traditional keyed lock.  When used a a keyless cage lock it becomes a great safety measure for anyone with a large Parrot.  It is also perfect for daily use with escape artists or when hiring a pet sitter.

Approximately:
Small Ball 2.5 cm (1")
Large Ball 4.5 cm (1-3/4")