Black steel hobble chain with swivel link in the centre to prevent tangles. It is used in conjunction with a pair of hobble straps (available in either Chrome Leather or Double Leather) as a restraint device or to teach a horse to ground tie.
My sister works for the manufacturer, and she purchased some for me on my birthday in 2020. They are sturdy, flexible and made of some strong stuff. Used to buy Kmart tubs that would only last a few months. I plan on buying more, if I ever need new ones in the future.