It is a tilt paltform that goes between a tripod/studio stand and a camera. It is basically a tripod head that only tilts one way, and does not pan. They are not restricted to wooden cameras. Linhof used them as well, at least into the '60s, and maybe later. SINAR still makes them. Both the Linhof and SINAR ones also pan, however the Linhof one I have used is required to mount the camera, while the SINAR one is optional.
Because of the bottom fitting, I'm not sure how useful this will be to anyone using a modern tripod, but I am sure someone out there would make use of it on their older tripod.