This small "magic arm" has a single large knob at the center that can be used to lock the center joint as well as the two swivel balls at each end. It basically allows you to position a small piece of equipment in any orientation and position within a 5-9" range of the anchor point.

Each end has a 1/4-20 stud with rubber topped compression nuts, but the box also includes a (max 2" jaw) clamp that has a 1/4-20 (and 3/8-16) mounting point, as well as a cold shoe attachment point with a double ended 1/4-20 female so you could mount the arm to the top of a camera or mount anything with a cold shoe mounting slot to the end of the arm.

The entire weight of the arm/clamp/adapter is just over 3/4 of a lb. The arm alone is 215g, the 2" jaw clamp adds 109 grams and the cold shoe adapter and double ended female 1/4-20 piece is 27 grams.

Once you lock the knob the entire arm and end balls are VERY rigid.
Most of the hardware is aluminum and stainless steel, but the main bodies of the arms appear to be steel (my magnet sticks well).

Overall I was happy with all three of the main parts in the box, and as a kit I feel it provides good value for the cost.