Know what this RR item is?

Looks like that container locking device, that holds the four corners of "double stack" containers together. Assume you found it near a RR track.

Hmmm...interesting. Actually a friend found it some years ago along an rr track.

Stack lock.

I've heard them referred to as Interbox Connectors. 

http://www.pacificmarine.net/m...terbox-connector.htm

Thanks for all the replies. Looks like my mystery is solved.

Thanks again,

More appropriately it is called a "Manual Twist Lock"

And yes they are used to secure containers together.  They are also used on container ships as well but normally just to secure the bottom tier to the hatch cover on deck.  The upper tiers use semi-automatic twist locks.  They auto lock when the container is loaded and only have to be manually unlocked when discharging!