The Chrome Plated Aluminum SHORT double socket arm has a socket at either end to allow a 1" diameter ball accessories to be connected.

Overall Length: 2.4375"
Socket-To-Socket Length: 1.75"

The ""U"" in the part number reflects product packaged in poly bag. For additional specifications, see components and drawings tabs.
Color:  Chrome Finish 
Ball Size:  1 Inch Rubber Ball 
Material:  Powder Coated Marine Grade Aluminum