Grown Up Tinker Toy - Jobo's Latest Camera Support
It is a Joby L-bracket. Metal - with a tough non-skid rubber covering on the camera plate and the upright handle. It is asbolutely non-slip. Grasp onto this handle and your camera isn't going anywhere you don't want it to.
There is a 1/4" threaded socket on the top of the handle and Jobo suggest that various forms of bracket can be screwed in there. I found that a simple piece of 1/4" steel threaded rod would couple a TTL cord and shoe to this and once you set the angle of the block, the rubber covering made sure it did not rotate.
The camera plate has an accurate Arca-Swiss channel in the bottom and numerous attachment points for standard 1/4" threads. There is also a wonderful strap attachment point at the RHS that means you can sling a camera in the same manner that the old Leica M5 was - it hangs vertically down at your right side. and when you put it up to your eye, your nose does not fight with the strap!