Yoke. It is comprised of two 1" diameter balls, each resting on smaller balls which roll on a spherically contoured seat. This gives the yoke its fluid motion. The bent portion that holds these bearings is made from 3/16 x 1-1/4" steel and is welded to a 1" diameter shaft that is 12" long. The adjustable housing is 15" long and is meant to be welded to a floor stand.
NOTE: You can also order replacement bearings in the Tools:Accessories section.