This K&F Concept magic arm made entirely from metal, is 25cm long from tip to tip and has a quarter inch BSW fitting at both ends. From the base of each end - the flat, rubber surfaces section where you might mount a camera, monitor or similar device - it is just under 24cm. To work it, you loosen the orange butterfly nut in the middle and this will loosen the ball fittings at both ends, allowing you to position it to your taste. If you loosen it further, it will loosen the rosette in the middle, allowing it to flex its 'elbow' as you can see in the photographs - the rosette means that the angle that you set the elbow to will stay once it has been tightened. This means that you can have the two ends as close as just a few centimetres or as far away as 24. With it being made from metal, you can tighten it quite a bit so that you don't get any slippage.
In addition to the magic arm, you also get a super clamp which will screw onto one of the ends of the magic arm. The superclam has two threaded holes in it - 1 x 1/4" BSW and 1 x 3/8" BSW - this means that you are not limited to using it with the magic arm.
The jaws on the superclamp are lined with textured soft plastic and will hold circular cross-section items with a diameter ranging from around 8mm up to 55mm at which point the ends of the jaws become parallel. The threads of the butterfly screw on the clamp are held in both directions so you cannot hold the jaws closed on something and just spin the thread.
A magic arm with a superclamp is always useful because you can screw anything you like onto the spare end and mount your smartphone or an action camera onto one leg of your tripod if you want to - taking time-lapse of setting up a shot provides good footage with a number of purposes. This unit is well made, solid and strong. The only downside of it is that you cannot spin the clamp's butterfly nut to hold onto things quickly but that is not important enough to lose a star in my opinion.