From B&H:
Turn any Light Stand with a 5/8" baby mounting stud into a platform for mounting ball head or pan-and-tilt tripod heads.
Add functionality to a light stand or combo stand by using the LS-BHA to attach a standard photo or video tripod head with a 3/8"-16 female mounting thread. By removing the locking knob, the adapter's receiver quickly converts into a 1-1/8" junior pin for compatibility with stands having junior receivers.
Get the Impact LS-BHA Baby Ball Head Adapter at B&H.