aluminum alloy, lightweight, wear-resistant, full of durability. Comes with 5pcs 1/4 screw holes and 1pc 3/8 screw hole. Powerful expansion function, suitable for most scenario requirements. Converter adapter, 6-way adapter, compatibility with 1/4 and 3/8 interfaces expansion. Side positioning column, firmly locking screws, effectively equipment from reversing, loosening and other problems.