The Manfrotto 131DD-14 Cross Arm with 1/4"-20 Mounts attaches to any support that has a 3/8" threaded stud. Two adjustable mounting platforms on the arm have 1/4"-20 studs which allow one or two cameras or tripod heads to be mounted perpendicular to the arm. In addition, the horizontal bar features a 1/4"-20 stud on each end, allowing mounting of two more cameras or accessories from the sides.