This adapter is has a double ball joint secured by a ratcheted handle and two 5/8" (16mm) stud s on eithe r side. One stud is tapped witha 1/4"-20 female thread and the other has a 3/8"-16 female thread for a variety of mounting options. Each stud is milled withsix flat surfaces to prevent your light fixture or any accessory witha baby receiver from rotating once the set-screw is secured. This adapter is identical to the double ball joint adapter withdual 5/8" (16mm) stud s (kg007212) but includes the camera-umbrella bracket (kg006411).