I believe you are asking what type of steel the Filarmonicas are made of, is that correct? If so, I'm not sure myself but you might check out the SRP Wiki, there you will find a great deal about the razor(s) as they are quite popular with a number of members here. In addition, I'm sure some of the members who have these razor's will chime in and provide an answer. It might be helpful to mention which particular razor you have.

Enjoy,

Joe