This is a simple stepped wedge for setting the intonation on a Floyd Rose.
Remove the back cover plate. With the bridge set at the desired angle, insert the wedge between the wood and trem. Loosen the trem springs to put pressure on the wedge to hold it in place. Adjust the saddles for intonation. Retighten the springs and remove the wedge.
In the photo (compliments of Buck) his trem pocket was wide, so he used a pice of bone to make up for the width.
restricting the trems movement make intonation just a standard job, eliminating the back and forth with a moving trem.