So check it out, remember the top handle rig I talked about? Well using the same parts you can mount any follow focus with a 1/4 inch mounting point to your Magic Arm! Check out the video to see how I did this with my D|Focus.
Not as many mounting options as the cinevate baseplate, but it is a fraction of the price. Get a couple if you can so you can use the same baseplate on multiple rigs, tripods etc.
These are great. There are so many uses for these arms so if you every switch up your rigging you will always have a use for one of these.