With two adjustable head platforms, the 3153 Double Head Support mounts on the center post of tripods with 3/8"-16 threads. The platforms feature 3/8"-16 screws, which allows a standard tripod head to be mounted on either or both sides. In addition, the horizontal bar features 3/8"-16 screws on both ends, allowing mounting of tripod heads from the sides. 23.5" (60 cm) long & weighs 3.50 lb (1.59 kg).