The wheels are in Titanium, the escapement is in steel.
FP is still trying other materials. He commented that he is at the beginning of the EBHP and thinks that it will continue to evolve over time and possibly be used with his other calibers.
In order to manufacture watches for the next 200 years they must be able to be serviced by a watchmaker. Materials such as the silicon are fragile and will not contribute to the life of a watch, perhaps making them unfixable. FP wants to keep using materials similar to the ones used in the 18th century because they have proven the test of time.
