The Aquatica TLC arm set 17501 gives you complete lighting control since it is made up of a 4" lower section, 8" middle section, and a 8" upper section.
Head adapter 17752 is used to attach Ikelite Substrobes DS-125 or DS-50 to the arm. Also included is the Aquatica TLC dovetail base that screws into the housing handles for mounting the arms.