Unstamped 8 3/4 X 10 1/2 Ligne friction jeweled bottom plate with balance cap jewel and shock spring in envelope marked 711. Five friction jewels.
I've been unable to identify the particular grade of this plate yet. It would certainly be a work saver in the case of a cracked jewel if you recognize the grade and need one. Cheaper and easier than rejeweling.
Or, if you are building your own movement you could save a lot of milling work by starting with this plate.
